Np203 to Np205 , transfer case swap

[devin bianco]

this might have been talked about before, but it would be nice for some clear information on it.

first here are some specs:
Ive got a 79 k10, sb350 going to a th350 going to a np203 full time no slip yoke.

we are doing a np205 swap, we have the truck down to frame with no current drivetrain. my main questions are regarding parts and driveshafts.

we have a guy wanting to sell us an np205 with no shift linkage and no adapter plate, how hard are these parts to find? and how much am i looking at for shift linkage and an adapter plate?

and then as far as driveshafts, would we be able to pick up driveshafts off any 80s k10 with an np205/th350?

we are not super concerned with price and we are pretty set on ditching the 203, reason being the full time 4wd + the fact that its chain driven + the one we have is junk. We also don't really want to mess around with doing a part time conversion as we feel like we are going to break even price wise on both options (front driveshaft is bad on the truck anyways)

we also know people that could make us driveshafts, but i know there's a few people on here with some tips and tricks to cut the price and workload down.

id love to talk to somebody who has done it, and just see what kind of stuff to expect/avoid.

thanks guys, and a side note this site is really helpful i am beyond thankful for the support you guys give.

 

[bucket]

You will want a 205 with the 'figure 8' mounting pattern. You will also want it to have the 27 spline input. You can use a 205 with a 10 spline input, but then you have to swap the input to a 27 spline or use a special coupler sleeve in the adapter. You cannot use a 205 with a 32 spline input.

The shifter isn't a big deal, you can buy used ones or upgrade to twin sticks from places like ORD or JB Fabrication. The adapters can be found new and used. So a lot depends on the specific 205 that you have found.

 

[bucket]

Oh, and the driveshafts are a big gray area. It all depends on your current yokes/flanges and the yokes/flanges that are on the 205 that you find. Many of them made after '79 have a slip yoke on the rear output.

 

[Bextreme04]

My truck has a 205 from the factory. If you dont have a shift linkage, I would recommend just getting an ORD twin-stick kit. You will also need to convert the front hubs to manual locking from the full-time hubs. I would think you can probably re-use the same driveshafts between the two transfer cases. If they both came off TH350's there is a good chance they have the same driveshaft connections. I don't think the 205 and 203 have different lengths. All trucks in 1980 got the NP205, so if you find a 1980 K10 that had a TH350 in it, you will find all the right parts you would need for a swap. The K20 drivelines would need some modification to work on your K10 axles.

 

[bucket]

A 203 case is longer and iirc, uses a different length front shaft as well.

 

[RoryH19]

A 203 case is longer and iirc, uses a different length front shaft as well.

Right, I looked into this for my 78 k10. For the swap need the 205 T-case, both driveshafts, shift lever, coupler/adaptor and I believe the cross member (can't remember for sure). I decided I didn't need a 205 that badly.
If I run across a 1980 donor for the right price then I might swap.

 

[devin bianco]

You will want a 205 with the 'figure 8' mounting pattern. You will also want it to have the 27 spline input. You can use a 205 with a 10 spline input, but then you have to swap the input to a 27 spline or use a special coupler sleeve in the adapter. You cannot use a 205 with a 32 spline input.

The shifter isn't a big deal, you can buy used ones or upgrade to twin sticks from places like ORD or JB Fabrication. The adapters can be found new and used. So a lot depends on the specific 205 that you have found.

quick question, would you recommend a different transfer case instead of np205?

 

[bucket]

quick question, would you recommend a different transfer case instead of np205?

Nope! With the early 4x4 th350 (very stubby output shaft) your options are either a 203 or a 205. If your 203 has issues, a 205 is the logical choice. I haven't looked recently, but it didn't used to be very hard to locate a complete 205 setup for a th350. Although I'll bet the prices are much higher now than they were when I bought a couple setups 10 years ago. I think I paid $100 for one and $125 for another.

 

[78C10BigTen]

Nope! With the early 4x4 th350 (very stubby output shaft) your options are either a 203 or a 205. If your 203 has issues, a 205 is the logical choice. I haven't looked recently, but it didn't used to be very hard to locate a complete 205 setup for a th350. Although I'll bet the prices are much higher now than they were when I bought a couple setups 10 years ago. I think I paid $100 for one and $125 for another.

Im still sittin on a figure 8 205 lol....

 

[TubeTruck]

I remember when they were $100 also, lol.
About 2 years ago I paid $250 for a figure 8 NP205 with a slip yoke. I'm browsing for a circle 205 and when I find someone who doesn't know what they got I'm going to scoff it up lol

 

[wanderinthru]

Im still sittin on a figure 8 205 lol....

What you talking about?

 

[78C10BigTen]

What you talking about?

Figure 8 pattern NP205

 

[wanderinthru]

Figure 8 pattern NP205

Thought you had made a deal on that and the 4 speed? Just needed to go get it?

 

[78C10BigTen]

Thought you had made a deal on that and the 4 speed? Just needed to go get it?

I did. That hasnt changed. I was simply saying ive got one since everybodys saying they are like hens teeth.

 

[RedneckDave]

this might have been talked about before, but it would be nice for some clear information on it.

first here are some specs:
Ive got a 79 k10, sb350 going to a th350 going to a np203 full time no slip yoke.

we are doing a np205 swap, we have the truck down to frame with no current drivetrain. my main questions are regarding parts and driveshafts.

we have a guy wanting to sell us an np205 with no shift linkage and no adapter plate, how hard are these parts to find? and how much am i looking at for shift linkage and an adapter plate?

and then as far as driveshafts, would we be able to pick up driveshafts off any 80s k10 with an np205/th350?

we are not super concerned with price and we are pretty set on ditching the 203, reason being the full time 4wd + the fact that its chain driven + the one we have is junk. We also don't really want to mess around with doing a part time conversion as we feel like we are going to break even price wise on both options (front driveshaft is bad on the truck anyways)

we also know people that could make us driveshafts, but i know there's a few people on here with some tips and tricks to cut the price and workload down.

id love to talk to somebody who has done it, and just see what kind of stuff to expect/avoid.

thanks guys, and a side note this site is really helpful i am beyond thankful for the support you guys give.

I did the same swap to my 79'. I used a 205 from a 74' K20, my rear shaft is from the same truck, just had to buy a conversion u-joint 1310/1350, the front shaft I sourced from a junkyard, used a 76' Suburban front shaft and it works perfect. I was lucky and the guy I bought the t-case from had the adapter plate and the sleeve for the trans to mate to the t-case. Pretty sure ORD offers the plate and sleeve on their website.