89 Suburban drivetrain swap

[Chevyrejects]

Hello everyone. I would like to see if I can get some information. I currently have a 3/4 ton 89 Chevy Suburban with a SBC 350/th400/np208 with a 10 bolt in the front and a corporate 14 bolt in the rear. I also have a 74 Chevy long bed truck that currently only has th350/np205 Dana 60 in the front and a 14 bolt FF with custom driveshafts. I am thinking of swapping the 1 ton axles along with the 350/205 combo for the 3/4 axles and the 400 tranny.The 400 tranny is starting to have some issues, and the 350/205 combo is still in good shape. The Dana 60 has the the ORD crossover steering.Would there be any issues or problems with the swap if I do go through with it? Would I need any special parts to complete the swap?
I do know I would need a 2wd gear box but is there something else I may need. Thanks to everyone in advance!!

 

[Justin V]

Well, are you sure that you have a np208 in the 89?

It should be a np241...

 

[Justin V]

I wouldn't put a 205 in place of a 241, is what I am getting at...

 

[diesel4me]

Why disable one truck to keep the other one going ?...unless one was a parts truck only,then I'd see the reason...otherwise why not just get the TH400 rebuilt ?..

 

[Chevyrejects]

Why disable one truck to keep the other one going ?...unless one was a parts truck only,then I'd see the reason...otherwise why not just get the TH400 rebuilt ?..

Don’t have the money right now to rebuild the 400. I also have to many projects at the house and the truck doesn’t allow for me to wheel with the rest of the family.

I built the truck when I had a smaller family and would go wheeling with my brother and sometimes by myself. My family has grown and the suburban is big enough for the whole fam. I will be putting in the 3/4 ton axles in the truck and try to sell it.

I wanted to swap everything from my truck over to the suburban so I could try to save some money.
I am worried if I just put the axles in that I would have to spend some more cash on driveshafts. I am not sure if the 400/241 combo is the same length as a 350/205 combo. Again so my concern is that the driveshafts won’t work if I leave the 400/241 combo when and if I swap over the 1ton axles

 

[Chevyrejects]

I wouldn't put a 205 in place of a 241, is what I am getting at...

You are correct it’s a 241

 

[swettysblazer]

I would think that a Burb has a longer wheelbase than a long bed, and the rear driveshaft wouldn't work.

 

[Justin V]

If it was me I'd swap the axles and fix the TH400.

If your pick up is a 1 ton frame, the rear spring perch width isn't the same as the burb... fyi

True 1 tons had 40.5 inch rear perch spread, while the 1/2 and 3/4 tons were 42.5 inch spread.

 

[diesel4me]

I believe the NP205/TH350 setup will not be the same overall length as the TH400/NP208 either...somewhere around 1981 GM made the different drive train components end up about the same length overall,close enough so the slip yokes would allow them all to fit up..

But the older trucks with cast iron transfer cases all had their own specific drive shaft lengths ..and as noted,the Suburban's shorter wheel base of 127.5" vs 131.5 for a long bed pickup will have a shorter drive shaft in the rear at least..

I swapped a NP-205 & and TH350 into a 77 GMC K2500 I had,that had a NP-203 & TH350,I had to find a shorter front drive shaft,the rear one bolted up OK though..

Another snag is the pinion might stick out farther on a 1 ton 14 bolt ,depending on the ring gear diameter..as well as the spring pad spacing..

I think rebuilding or finding another good TH400 would be a lot less labor!..

 

[Justin V]

The burb shafts would work with the other axles, especially if you lift the burb. May need an ez inch to push the front axle forward and/or the rear axle back a tad.

The d60 has a longer pinion than the 10 bolt, don't know which 14 you have in the burb, and I don't know if the 9.5" version is shorter pinion than the 10.5" full floater.