How hard is it to swap my 3.08 gears to 3.73 gears?

[peats]

your problem is't the gear ratio or tire size. it' the 305. get rid of it.

 

[Ewhitaker0020]

your problem is't the gear ratio or tire size. it' the 305. get rid of it.

It's on the to do list. But I think both are problems.

 

[Ewhitaker0020]

your problem is't the gear ratio or tire size. it' the 305. get rid of it.

It's on the to do list. But I think both are problems.

 

[RecklessWOT]

Maybe so.I have 3.73's and a 350 in a fulltime k10 and it does pretty good. I've had an overload of 2 tons in the back and it pulled it.Too much for a 1/2 ton to haul.I'm sure I'd lose too much fuel economy for my liking with 4:10's but if you need it, you need it I guess.

Don't you have a 3 speed though? OP has a 700r4, with that super tall overdrive (and that terribly long 1-2 shift) you need a lot shorter gears than with a TH350 or TH400. For those transmissions, 3.73s seem plenty short, but with a 700r4 even 4.10s seem about just right with stock size tires, start going bigger and even those start to feel mighty tall. I can only imagine how much it sucks with a 305

 

[Ewhitaker0020]

Don't you have a 3 speed though? OP has a 700r4, with that super tall overdrive (and that terribly long 1-2 shift) you need a lot shorter gears than with a TH350 or TH400. For those transmissions, 3.73s seem plenty short, but with a 700r4 even 4.10s seem about just right with stock size tires, start going bigger and even those start to feel mighty tall. I can only imagine how much it sucks with a 305

The 305 has always felt so weak. I never knew the 3.08 gears were part of the problem. I'm all about saving gas money, but it's really destroying the driveability of the truck. And yes, the 350 I plan on putting in it in a couple years will help tremendously, but I'm hoping to do something sooner that will help.

I called a local mechanic to ask him how much to swap the gears and he said $300-$500 per diff. And that's just for labor. Way too expensive if you ask me. That puts me in $900-$1300 after buying the gears. I can buy a 350 for less than that. And I can put that in myself.

 

[RecklessWOT]

The 305 has always felt so weak. I never knew the 3.08 gears were part of the problem. I'm all about saving gas money, but it's really destroying the driveability of the truck. And yes, the 350 I plan on putting in it in a couple years will help tremendously, but I'm hoping to do something sooner that will help.

I called a local mechanic to ask him how much to swap the gears and he said $300-$500 per diff. And that's just for labor. Way too expensive if you ask me. That puts me in $900-$1300 after buying the gears. I can buy a 350 for less than that. And I can put that in myself.

350 won't make that much of a difference. Yeah the 305 is underpowered and a 350 is a much better engine, but what are we talking here, 25-30HP? 3.08s are SUPER tall it will make a HUGE difference to go with something as drastically different as a 4.10. Then later on with a 350 it will be even better. My truck came with a fuel injected 350 and 3.73s, I still decided to go with 4.56s. Was gonna do 4.27, but figured with my 33s the shorter gears would be even better.

Yeah a 350 will be nice, but it's not a big block or anything. A lot of these comments are from dudes with 3 speeds, they usually aren't personally aware of just how terribly tall the gearing of a 700r4 is to begin with. Trust me, do both. With the gears you might even think the engine can wait. With how tall the OD is on the 700r4, it won't even be revving out at highway speed, it will just feel like a normal vehicle for once. Trust me...

 

[Rusty Nail]

4.10's really picked up the bottom end. My truck was a Calif smogged 150HP 350. An overdrive would have really helped though. The truck didn't have too much more to give after about 3500 RPM.

How fast were you goin ?

 

[mcarlo86]

350 won't make that much of a difference. Yeah the 305 is underpowered and a 350 is a much better engine, but what are we talking here, 25-30HP? 3.08s are SUPER tall it will make a HUGE difference to go with something as drastically different as a 4.10. Then later on with a 350 it will be even better. My truck came with a fuel injected 350 and 3.73s, I still decided to go with 4.56s. Was gonna do 4.27, but figured with my 33s the shorter gears would be even better.

Yeah a 350 will be nice, but it's not a big block or anything. A lot of these comments are from dudes with 3 speeds, they usually aren't personally aware of just how terribly tall the gearing of a 700r4 is to begin with. Trust me, do both. With the gears you might even think the engine can wait. With how tall the OD is on the 700r4, it won't even be revving out at highway speed, it will just feel like a normal vehicle for once. Trust me...

I couldn't agree more....about the only gearing worse for a 700r4 than 3.08's would be 2.76's. Auto manufacturers did some dumb stuff back in the 80's (especially early 80s) trying to get the best number on the fuel economy window sticker possible. Our local Chevy dealer back then wouldn't even order in a pickup with taller gears than 3.73's. He used to say that all you end up doing with those highway gears is have to have your foot in the throttle harder and then get worse gas mileage.

 

[Octane]

.

 

[Ewhitaker0020]

Does anybody know the year range of axles that will fit My 84 K10?

I found a 2000 Z71 Silverado with 3.73 gears. Can I swap over the axles?

 

[Rusty Nail]

The axles got better in 91 I think.
Bigger, gooder bearing some ****.
You want so stick with OBS trucks, likely capped thru 93. Maybe a 94?
Old Body Style.
89-93 is the ideal target range.
Anything is possible but I assume you want something that will bolt in haha.

Think 81-93 or near there
Around that. Max range.
"Rounded line" trucks.

I never knew the 3.08 gears were the problem. I'm all about saving gas money, but it's really destroying the driveability of the truck. I'm hoping to do something sooner that will help.

I called a local mechanic to ask him how much to swap the gears and he said $300-$500 per diff. And that's just for labor.

Way too expensive if you ask me. That puts me in $900-$1300 after buying the gears. .

Thats about right and it's what we are talking about. That much money.

If you want positrac add more.

Consider this amount very seriously for CUSTOM NEW.

OR buy used 89-93 or 94

IF you found a guy that actually said he would do it, be real nice to him. Gettin an axle rebuilt costs 1500 if youre not gonna touch it. That price includes install or removal.. They are really heavy and require big expensive machines that you . dont . have.

 

[Rusty Nail]

Hope this helps!

 

[Ewhitaker0020]

The axles got better in 91 I think.
Bigger, gooder bearing some ****.
You want so stick with OBS trucks, likely capped thru 93. Maybe a 94?
Old Body Style.
89-93 is the ideal target range.
Anything is possible but I assume you want something that will bolt in haha.

Think 81-93 or near there
Around that. Max range.
"Rounded line" trucks.




Thats about right and it's what we are talking about. That much money.

If you want positrac add more.

Consider this amount very seriously for CUSTOM NEW.

OR buy used 89-93 or 94

IF you found a guy that actually said he would do it, be real nice to him.

I found a 1/2 ton axle out of a 92 for sale. So it should bolt right up?

He's a good mechanic/guy. I just wanted to make sure I didn't get the "I don't want this job price"

 

[Rusty Nail]

Yes?

Without more info.

The concerning differences now look like brake parts.

The brakes EV.

Oh youre gonna get the "this job is a freaking pain in the ass" price.
Nobody wants to do it lol.
It's gonna cost more than you think.
But you might as well quit dogging your 305 because thats not the trouble.

Not even you want to do it and it's YOUR truck!
Lololo

Half ton axle is 5 or 6 lug.


You can buy a rear 2WD axle pretty close to want you want and maybe only gear change the front but you could end up with a 5 and a 6 lug bein cheap.
Maybe an 8 and a 6?
That would be fun.


The brake parts.
The brake parts.
The brake parts.

If you find or found a 92, 4wd, with 3.73s for $300 or whatever. Run buy em and pay to fix the brakes during install.
Still be out another grand.

Gotta be patient and maybe look a long time.
Everybody else wants that too though. Gotta hurry before they disappear!


Don't forget about the brake parts.

 

[Grit dog]

I've got a 1980 K25 with 350/TH400/NP205, 4.10's and 35's. It is barely noticeable when I have 2 yards of 3/4" minus in the bed(~4,000lbs)... it accelerates fine up to highway speed just a little slower than with an empty load. I've also pulled a 5,000lb travel trailer over the cascades to go elk hunting at 65mph with no issues. I had a C20 with 4.56's also and it was definitely more peppy, but it was wound out and screaming by about 60mph. I think you would be very happy with a 350 swap and 4.10's... it would certainly be a huge improvement

I also see rolling chassis for sale in my area pretty regularly for a few hundred dollars. You should be able to buy a rolling 3/4 ton chassis for $300-500 dollars, take the front and rear drivetrain out and sell the rest.

I think we have it good out here for finding old vehicles and parts comparatively. But icbw.
Agree w OP, gears will help immensely. And with the 700 trans he can go deep and still maintain highway drive ability.
I have the same gears and tires combo as you and IMO it’s not a highway driver. Maybe spoiled since OD transmissions have been the norm since I started driving, but I didn’t like road trips with deep gears and a 3 speed back then either.
It’s a crap shoot on a budget. Unless you find a cheap set of axles or a roller like you suggested gears are as expensive as a motor giver take. As the OP found out.
I think it’s plan for the future either way and either mod will get him halfway there. Personally, built used small blocks are dime a dozen and I’d go for the HP over the gears first, since he doesn’t tow heavy.