I have a 1978 chevy truck with 6 inch lift 35 inch tires and a 350 with 350 hp, I have a 1986 th700r4 what upgrades would i have to do to hold up. and would a np208 work with my truck, or would i have to go to advanced adapters and keep my np205.

are you attempting to put the 700r4 behind the 350 in the 78 and keep the 205 that is in the 78?

if so then you can get the 700 rebuilt, put billet servos in it, high quality clutches and if you are feeling like spending big money upgrade the gears and pinions with either 4l60e/65e components or go after market. If i recall Jet makes those for the 700.

you will have to have an adaptor from advanced to make it work or you could try jerry riggin something with the 350 adaptor that you have now, assuming thats what was in front of the 205.

the transmission thats in my truck now is a sm465 which is a 10 spline, or should i find a 27 spline np205 with a th350 adapter

there is a company who makes a spacer for the np205/th350 adapter for the 700r4 ive found it alot easier to install the spacer on those transfercases with the round flat flange 4 bolt front driveshaft configuration (usually 30 spline output that could be converted to 32 spline very easally) because of those odvious trans pan to big assgoofey cv shaft interfearance issues. however if you do have a small 4 bolt yoke ive had the best luck running the advance adapters output shaft with a factory th350/205 adapter, even though you have 10 spline transfercase i know where you can get the adapter spud shaft ( what connects your trans to the t case) with 10 spline on one end and 27 spline on the other. thanks in here all week :D

For the tranny, get a high energy rebuild kit. Also get kevlar 2/4 band, use 400 grit wet/dry sandpaper and scuff up the carrier (where the 2/4 band rides) in a criss cross pattern. Vetter servo and make sure the accumulor pin is clearanced properly. I would also replace the accumulators and go with a pinless accumulator. Up grade the pump to at least a 10 vane, altough a 13 vane pump would be better. There are a couple of mods you can make, some grinding on the boost valve in the pump, a spring in the governor, and a spring behind the trottle valve. I highly recommend a new torque converter, and go with Raybestoes Z-pack for the 3/4 clutch pack. Super strong. Install a drain plug in the tranny pan, and flush out the rad cooler, install a auxilary cooler. Then, of coarse, replace any wore hard parts. And for added security, install a tranny temp gauge in the pan. There are other and more things you can do. But that should get you pointed in the right direction. Do a web search for a Raptor 700R4 tranny. The site that comes up has tons of info and sells just about everything you need. I never dealt with them, but the site is great.

I've dealt ith them for some small parts for my TH350. Nothing but good things to say.

thanks for all the info