350 turbo with 203. I want to keep my 350 turbo and get a 205 behind it? Please help.

[BearKing]

I have a 1976 Step side with the 350 turbo with the 203. I want to put a 205 case on the 350 turbo. What do I need to look for in the boneyard? Thanks in advance fellas.

 

[dvdswan]

I don't remember if the tailshaft on the trans is different but it probably is because the mount is different. But you would need at a minimum the mount between trans and t/case and the t/case. I do know that a 1980 Blazer came with that combo if you ordered it with locking hubs.

 

[Bextreme04]

It was an option for many years. You just need to find one attached to a 350 already. I think I have seen two or three trucks and at least one transfer case by itself for sale locally in the last week with that combo.

 

[Turbo4whl]

Couple things to think about. The rear drive shaft needs to be longer. The front shaft from the 203 will not match the 205. Both the 203 and 205 for a TH350 have the same spline count, 27.

Easiest would be locating a donner truck with all the parts you need. Check this for good info:

Off-Road, Click here

 

[Juggernaut]

I have exactly what you need if you're interested. Adapter, splined coupler, even the 205 input shaft if you need it

 

[BearKing]

I have exactly what you need if you're interested. Adapter, splined coupler, even the 205 input shaft if you need it

I’m interested but how would I get it here?

 

[BearKing]

I have exactly what you need if you're interested. Adapter, splined coupler, even the 205 input shaft if you need it

Do you know if the transmission crossmember is the same or will I need to locate one? I think it would be the same but I haven’t crawled under there to check.

 

[ali_c20]

I did the swap on my K5 th350 /np203 to np 205. Driveshaft length front and rear is different, crossmember is the same. Adapter, splined coupler etc. is needed.
Best would be go to a junkyard and get all the parts from a donor truck.
You could also call Off road design, I bought all my parts for the swap there. They are very helpful.

 

[Juggernaut]

You will need to check the input spline on the transfer case. Most came from manual transmissions, 10 spline I think. Automatic I think is 27 spline. Do you already have an NP 205?

 

[Juggernaut]

Weight of the adapter, sleeve, and NP205 input shaft is about 30 lbs, and will fit in a 12 x 10 x 8 box, so it can ship UPS. Not sure where you live, but you can look up Evansville IN to your location for the shipping cost

 

[BearKing]

You will need to check the input spline on the transfer case. Most came from manual transmissions, 10 spline I think. Automatic I think is 27 spline. Do you already have an NP 205?

I don’t have a 205 case. It’s a 350 turbo attached is the factory 203.

 

[Juggernaut]

I think the entire transfer case would be too expensive to ship. I know it would be too heavy for UPS. If you can find one locally and need the adapters, I can help you out

 

[Br 549er]

Sorry to bump into this old post but I’m wondering if it matters if donor parts came from a 1/2, 3/4, or one ton vehicle? Shouldn’t matter should it?

 

[Strick]

Shouldn’t matter should it?

The transmission output should be the same as long as you are using the TH350. The TH400 output is different as is the SM465 manual. The output shaft on the NP205 could be a fixed or slip yoke style as well. IF you had two trucks with the same wheelbase & TH350 then you should be able to use the NP205 and rear driveshaft from one to the other.
Welcome to the site; by the way. You should find some similar thread topics like this here also.

HS

 

[Br 549er]

Thank you! I’m learning and appreciate your insight as well as others on here…
I’m just trying to decide which route I’d like to take on my project… currently have a 76 k25 gmc that I’ve removed the body and I have a 1980 gmc 1/2 ton pickup I want to use the body for the 76 frame…
Current drivetrain in the 76 is the original 4 speed with a NP205 and debating on whether I should convert to an automatic possibly and also put a crate 454 in for power… this leans me to a th400 transmission I’m thinking but that’s where I’m struggling on what exactly to look for to make that change… finding donor vehicle with what I need is doable I think but if it’s a half ton donor I’m guessing that would have a th350 transmission and not the th400…? I’m not dismissing the idea of a small block either but always liked the big block in this kind of setup… just going to be a driver really nothing more… fun to play
Thanks