Can you convert 4wd to 2wd... without changing front suspension?

[AuroraGirl]

This may seem like a retarded ass question, but beings the front axle (d44 in this case) in my dads 75 k25 is fine, his engine is fine, but his transmission is toast, and he needs a lot of u joints even if he fixes the transmission and his Np203 is probably a little worn out anyway.. I wanted to know if you could just find a 2wd tranmsission and appropriate driveshaft and make them work? The truck sits higher like mine, so likely has HD springs I would presume.

I was just asked to find a reasonable way to fix the truck since the transmission is ripperoni. I have a th350 mated to an np203, but a half ton, but with the front end components he needs and the primary uses of the truck as it stands, a 2wd even if not permanent wouldnt be a bad life for it, just so it stops sitting. but I dont know if there would be ramnifications of the front diff not having a driveshaft holding against the bearing(maybe the hubs could be converted to have lockers, then left unlocked?)

Its a longbed wheel base 4x4 3/4 ton which has its original drivetrain and axles, 44 up front, 14 in the rear, and 400 SBC with its np203/th350 pairing.

as far as putting a trans, th350 or 700r4 can be found rather easily around here for not bad, 2wd versions recently not so bad at all.

So even if this seems stupid or just enormously weird, any insight would be appreciated. I never even heard of the idea but unless a np205 th350 adapter isnt expensive and has the same driveshaft lengths as a np203(which I doubt) and as the original sm465 (which I would really doubt) off my 77 or my 80, I dont see a way to use my hardware without equally needing to size up new driveshafts or going so deep that he could have just had a shop fix/replace whats broken i got more than one th350 for a 2wd application, not sure if being from a car would mean a smaller shaft or anything but its worth noting.

We have a neighbor nearby that has been eyeing up some of my doors and I could see what he has, but hes mostly got later 80s square stuff

It should be noted my dad currently has a 96 silverado that.. uh.. has seen better days but if it had an untimely death, it has a 4l60e but half ton - that being said, an electronic transmission isnt out of the consideration if the electronic controller isnt hard to do. My cousin has a late 80s F body and he is looking to go from his 700r4 to a th350, for some reason, but eh...?

 

[77 K20]

So his truck needs a TH350 and maybe a NP203....

And you have a TH350 and a NP203...

I've read this several times. Unless I'm missing something just put your transmission and transfercase in his truck. Be way easier.

Since yours was a 1/2 ton then maybe you'd need to swap yokes on the transfer case. U joints are pretty cheap for the rest of it.

 

[Grit dog]

I'm rather confused by this as well...
Yes can drop a 2wd trans, 2wd driveshaft (and possible a different cross member), and the back half is now a 2wd truck.
But then you still have to deal with the front axle anyway, like you said putting locking hubs on it (to keep from having to fix the rest of the junk front axle, u joints etc, presumably?)

What you CAN'T do is run a 203 long term with a missing driveshaft (usually the the front) in HI Lock. It will wear out the transfer case.

 

[SquareRoot]

The worst of both. A useless 2wd truck that rides like a 4wd truck. Perfect!

 

[Grit dog]

I have a th350 mated to an np203, but a half ton,


as far as putting a trans, th350 or 700r4 can be found rather easily around here for not bad


We have a neighbor nearby that has been eyeing up some of my doors and I could see what he has, but hes mostly got later 80s square stuff

Unless any of these options is a known good transmission, there's a good chance that some 30-40 year old auto trans that has been sitting around has issues already.
I get not wanting to spend more fixing 1 thing on an old truck, that by the description, has also been neglected, than it's worth. But what's your time worth to possibly find out you just installed a bad transmission or 2, plus the other supporting mods or repairs?
And even if it's good, or the second or 3rd one you install is good, or you have one rebuilt, sounds like that leaves you still with the bad T case and the expense and time of locking hubs and/or u joints.....and what else does the truck need? I'm sure all the wiring is good, it's not rusted through the floor boards, brakes are great, etc?

Your gut already tells you that this is not a fruitful venture. Listen to your gut.

 

[AuroraGirl]

Unless any of these options is a known good transmission, there's a good chance that some 30-40 year old auto trans that has been sitting around has issues already.
I get not wanting to spend more fixing 1 thing on an old truck, that by the description, has also been neglected, than it's worth. But what's your time worth to possibly find out you just installed a bad transmission or 2, plus the other supporting mods or repairs?
And even if it's good, or the second or 3rd one you install is good, or you have one rebuilt, sounds like that leaves you still with the bad T case and the expense and time of locking hubs and/or u joints.....and what else does the truck need? I'm sure all the wiring is good, it's not rusted through the floor boards, brakes are great, etc?

Your gut already tells you that this is not a fruitful venture. Listen to your gut.

Its not that its not worth it, its just that its not mine and he doesnt want to go the spensive route if possible

The trans, because of how cheap they are to rebuild, i would prob have rebuilt or maybe take the opportunity to YOLO myself at a th350.

But that does lead me back to original, could it be made 2wd? The only reason I ask is that would mean I can cut out the t case which im gonna be honest i think has issues(it got drove a lot without a front driveshaft when the u joints got real bad) and beings it needs damn near every front end u joint, If I could find any trans for a 2wd that bolts to a SBC that would only mean I need to worry about the driveshaft which I do have a few of varying lengths and of course cros that bridge when get there kinda thing

I have a d44 with manual lock hubs,I dont know if I Could Just transfer the spicer hubs over to a all time axle or even buying a set wouldnt be terrible if I looked on fb (I see them here and there)
but this is all a moot point if Its not really a feasible idea

The truck actually isnt bad rust wise, the only bad spot was the immediate foot area was rotted away, just on the driver. Probably muddy from montana ranch days and never cleaned. BUt the cab is otherwise paint ugly just kinda exists. The brakes need work because the rears werent hooked up, but it would ultimatley be a lot less than my square to get road worthy and if he gives it to me, It would allow me to get a running 3/4 ton truck that I can pull things with a little more appropriately than the half ton f150

Beigs it has a dump bed... very versatile me thinks. 2wd wouldnt be killer, gas is gonna suck anyway, but can that crazy idea even work?

 

[AuroraGirl]

I'm rather confused by this as well...
Yes can drop a 2wd trans, 2wd driveshaft (and possible a different cross member), and the back half is now a 2wd truck.
But then you still have to deal with the front axle anyway, like you said putting locking hubs on it (to keep from having to fix the rest of the junk front axle, u joints etc, presumably?)

What you CAN'T do is run a 203 long term with a missing driveshaft (usually the the front) in HI Lock. It will wear out the transfer case.

oh okay. Well I do appreciate that fact. I definitely dont view this as long term. For the time being he wanted help with ideas for how to make it a useable truck instead of just sitting doing nothing. Fortunately its not in a spot where it is rotting it just stays with inflated tires and a bunch ofrebar on the back. If I can tell him to keep an eye out for a th350 or th400 2wd for a truck maybe we can piece it together so its functional.

Also @SquareRoot yes Im aware its gonna ride like ass but i would like to point out the only two squares ive ever been in ride like ass and that was one of them

Infact, that was the second vehicle ive driven on roads

As a teenager no rear brakes a little bit of sponge with a 8k pound truck(there was al ot of heavy **** on it then LOL) was a little frightening

But he doesnt really want to put too much, being it needs so much and I havent even told him my opinion on his T case..

Also just because its been in the family since 1974 its a little sentimental. just like my square since 79 or 80 whenever my grandpa got it.

The front axle isnt worn on the 75 I just feel if I made it a 2wd monstrosity i would be helping it out a bit by putting lockout hubs on so it can spin free. The thing is just sitting with the caps off at the moment(my dad hasnt exactly put a lot of long term thought into how it sits..)

when I was with him years ago the last time he used it pretty much at all, I was with when it started making loud noises and we had to baby it a few miles back. I believe, from memory, the chain probably skipped or something related to the differential because it didnt want to play nice on pavement and didnt sound great. Thats when he disconnected the shaft and drove it for a little too long in that state.

Minus 3 parts of the hub lock assembly, I have two spicer hub locks for a d44 so unless there was something special I should be able to make that work, presuming I can find the parts i need replacing.(the little cam piece with two wings that push on a gear in the hubwhen you turn the cap, i think) a snap ring and one of the gears

 

[AuroraGirl]

obviously needs to be pulled and built but I have two 2wd BOP transmissions sitting in cars rotting away that could use homes
a th350 and a th400, but the th400 is a console shift (if that mattered)
and also technically a th250 or whatever the step down was, but not even considering that.

Other than a adapter plate is that something that would work or does a car th400/th350 need different internals to be used for a 3/4 ton truck

 

[SquareRoot]

its gonna ride like ass

Well, if you put it that way...

 

[AuroraGirl]

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[Ricko1966]

Can anyone verify if pinion angle is the same 2wd and 4wd. If pinion angle is different you will have to twist the rear-end or raise/lower the 2wd transmission accordingly. Otherwise it will not just ride like ass, it will vibrate like piss.

 

[AuroraGirl]

Can anyone verify if pinion angle is the same 2wd and 4wd. If pinion angle is different you will have to twist the rear-end or raise/lower the 2wd transmission accordingly. Otherwise it will not just ride like ass, it will vibrate like piss.

i would think spring pack choice would be a big determiner as to the height of the truck normally. It sits rather high, so I suspect the angle will be different, but thats doable enough. BUt if its rotated too much, doesnt it want to "hop" by going down the road

 

[Ricko1966]

That's not what pinion angle is and ride height doesn't determine it,if you drew an imaginary line through the center of the engine and transmission,and that line was parallel to the ground ,not canted up,not canted down. Now your pinion with an imaginary line would have to be level to the ground also. If 1 is level and one is canted up or down it will vibrate. Put an angle finder on the pinion yoke put the angle finder on the transmission tailshaft,if they match,no problem If they don't match you need to shim the transmission or rear-end until they do. IDK if pinion angle is different on 2wd and 4wd I also don't know if the engines are at the same height and angle.

 

[AuroraGirl]

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i see what you mean

i was indirectly talking about that, too, but just a ddifferent way. Basically, all things considered as is on the truck at the moment, i would say that the transmission choice in a perfect world assuming the driveshaft was the same..lol wish... the height of the output of the trans will likely be different which is probably going to be the wrong pinion angle as you describe. it would possibly be right but eh. Definitely important to think about

 

[77 K20]

Don't 2wd long bed trucks use a carrier bearing/two piece rear driveshaft since the driveshaft is too long without a transfer case?