I have an 83 GMC Jimmy with a 6.2L. Diesel and a 700R4 transmission with a NP208 transfer case. I am having troubles with the auto trans and would like to go to a manual trans, but I have not been able to get any info from any mechanics or salvage yard people. Did GM mate a diesel with a manual trans from the factory? And if they did, what is it. I still want the good fuel milage. I would appreciate any info that I can get.
If they did, it would have been the SM465, a 4spd with granny low. I think you would have to change your transfer case in order for it to work though. Fuel mileage probably wouldn't be as good though, because the high gear is only 1:1 not .7:1 like the 700R4.
my truck was a 84, 3/4, 4x4, disel, 6.2 with the sm465 and np208 but had a 545 swapwd in, but im shure evreything was stock except the engen when i bout it and years ago my dad had a mid 80s 3/4, 4x4, 6.2 desel with the same trans. and t cace i have in mine
like tx_jeeper said, it would be about he same as if you ran your truck in third gear. And swaping to manual would be alot of work to do. Have you looked at swaping to TH350 or TH400 trannys. both 3 speeds, the 400 is heavier but much stronger.
Yes, SM465 to NP208 for half ton and SM465 to NP205 for HD 3/4 ton on up.
You can swap to a SM465/NP208 or SM465/NP205 pretty easily. All you need are the driveshafts, the crossmember, the bellhousing, the Z-bar/clutch linkage crap, the pedals, and the steering column for a manual transmission. Everything is pretty easy to do in the grand scheme of things. The hard part is finding all the parts.
If you use a NP 208 t-case behind the SM465 i don't think that you will need new driveshafts. This is only under the condition that you use the same model t-case that you have attached to your automatic transmission. I swapped from a TH350 to a SM465 (NP 205 in both applications) and used the same crossmember, driveshafts, and even the same holes in the frame to mount everything up to. The reason that I say I think you can resuse the driveshafts is because the TH350 and 700R4 are about 1.5" different in length. This difference in length should be able to allowed in the slip splines of the driveshafts.
The TH350 and SM465 are different lengths, however GM made the adapters different lengths so that the driveshaft lengths would be the same (provided same model t-case was used). When I did mine i simply swapped in the manual pedals, added the z-bar bracket to the frame, and swapped the flexplate for a flywheel. I left the automatic steering column in and just removed the shifter. Since i kept the TH350 and NP205 combo I can swap back to them in a matter of hours if needed.
I had a 6.2/ 208,sm465 and swampped in a turbo 400. I wouldnt recomend doing the swap to the 465 unless your going to use it primarily for 4x4ing. I couldnt stand shifting 3 times before i got through an intersection the tranny really wound out the diesel . Just my 2 cents though. If your intrested i got all the parts at my house mabey we can make a deal or something.