automatic overdrive or standard swap?

[shoooter]

I am looking for info on if there is a overdrive unit i can adapt to my turbo 350 auto tranny. the truck has a 350ci with a 208 tcase i believe. the other option would be a swap for a standard, one ones would bolt up to it. thanks

[Russell]

An 95+ NV3500 would fit the bill. Pretty similar strength to a 700r4 in my opinion, and nice close gear spacings. The trans will physically bolt straight in as long as you get a 27 spline version. Your t-case will bolt straight to the trans, and since it is the same length as the TH350 / NP208 combo, you should be able to re-use your original driveshafts.

Tricky parts include the shifter and the hydraulic clutch retrofit. The problem with the shifter is that it sits quite a bit further back towards the seat as compared to an SM465 that would have come stock in the truck and interferes with the NP208's shifter. The shifter has room to stick out, but there is next to no room for a shifter boot. The hydro clutch just requires some ingenuity on your part. I personally got the dash bracket from a 96 Chev with an NV3500 and cut it out / welded it to the inside of my 86's dash after drilling a hole for the master to go through. I then drilled a hole in the clutch pedal and installed a bolt with the head cut off / a hole drilled through the side for the master cylinder to hook onto. The geometry isn't perfect, but is close enough that the clutch still actuates easily.

I personally avoid automatic transmissions as much as I can.

[shoooter]

ok i should have said this is gong into my 72 gmc. but it shoudl work if i already have the turbo 350 in there

[special-K]

i don`t know if you want o/d with your tall tires.What tires and gears do you have,again?

[shoooter]

i have 38.5 x15.5 boggers on it right now and 4:10 gears. i would like to go back down to a 36 i think for tires

[special-K]

Ok,I like the 4L80E.it bolts to the same pattern.but.I have one in a`91 Suburban 3/4t diesel 4wd mated to a NP241.That`s the only year for a RH drop transfer case and 4L80E.But,they mate the same as the late NP205 and NP208.the GM diesels had manual injection through`93.I`m not sure what year the 4L80e started.the diesels would have a stand alone computer/controller for the trans.

[shoooter]

what are the best trucks to look for to get the trans?

[special-K]

A`91 4L80E from a 6.2 diesel will have a stand-alone computer.Otherwise You`d need to spend about $700 on an aftermarket trans controller.There are also 4L60Es,I just don`t think there`s a stand-alone application.You need to know your 208s spline count,which shouldn`t be a problem.The later 700R4s with a "K" case is another choice.Basically.any 5spd manual from a 4wd 88-up is what you`d want.There`s the NV3500 and heavier NV4500.