[Truckhead]

Got a 79 GMC 4WD. Currently it has a manual trans with a NP-205 transfer case, i know this because of other info and pics i got off this site. What I had in mind was an automatic trans swap. Which would be a better choice TH 350 or 400? Clearly I need a trans with the correct tail piece as it bolts directly to the 205. Will any 350-400 4WD 'bolt up' ? I'm not sure how many configurations of this particular trans there are that mate to a NP 205. Would this be considered a relatively straightforward swap? Any info would be greatly appreciated, Thanks!

[Crosley]

welcome to Hotrodders.com

I edited the thread title to provide the members here an idea of what your question is about rather than simply "Auto?"

[Truckhead]

Thanks, kinda new here

[louis165]

Your best chose would be th350 with 208 t.case the 208 has lower gear ratio in low range .try and get it all together .drive shafts cross member shifter however to do this you would almost have to find truck with the parts still in it ... To just change out the trans you would need the correct adapter and splin count the th350 has 27 splin and sm465 I think is 10 splin

[Truckhead]

Yeah I considered a 'donor' truck was hoping for a relatively easy swap, think you're right on the manual trans spline count also

[louis165]

Check with advance adapters they should have what you need to swap trannys out .wharf gear ratio do you have the stock gears are around 2.73 .and what size tires

[louis165]

I tried to post pictures of the adapter that you would need .it is a factory adapter check on eBay that's were I got mine . Then you can swap out the input gear on your 205 to a 27 splin .the th350 and adapter is 25 inch long . Plus 1 3/4 tail shaft . Hope this helps drive shafts should be ok but you'll have to measure and make sure

[Truckhead]

yeah 2.73 gears and 31x10.50 tires. Looks like Advance Adapters has what I need for the conversion. Thanks very much louis165, I appreciate it!