th 350- turbo 400

It might as long as it is a 4x4 TH400 it is not just a short shaft 400 with the extension removed. Also the other difference some of the TH400's have a heavy duty output shaft. I have run into both many times, measure the output on the TH400 and compare it with your TH350 If you don't have the TH350 out yet let me know and I'll measure the two so you can be sure. I have both types sitting around here...

The splines are likely different on output shafts. I think if i did anything I would consider swapping in a 700R4. Get a 4x4 version that has a HD case which can be easily spotted by it having a bolt on casted for bottom torque converter cover. This will give you OD and a much deeper first gear too (3.06 vs 2.52 for THM35o and 2.48 for THM400) and 700R4 does not need a computer to work and you could get a shifter out of a 81 on than had a 700R4. The 700R4 is basically a modified THM350 as it is mostly based off of it and they can been found with 27 spline and 30 spline tranny input shafts. The early ones have 27 spline and you want to avoid those. The later models are sound trannies if properly used and cooled.

----------------- TheSnoMan.com

Ok well my th350 went out and i found the turbo 400 on ebay and its cheap and they say its ok, i realy want to put a manual in it but i just dont have the money right now...i asked the people to measure the ouput for me and i will let you know. i really appreciate your help, and the 400 was out of a 4wd that rotted away...

Ok well my th350 went out and i found the turbo 400 on ebay and its cheap and they say its ok, i realy want to put a manual in it but i just dont have the money right now...i asked the people to measure the ouput for me and i will let you know. i really appreciate your help, and the 400 was out of a 4wd that rotted away...

I do understand money flow problems but now is the time to fix it right if you can. If you want to install a stick the SM465 was used thast year (and from about 67 to 87) so bellhousing and trannies are not too hard to find. 700R4 have been out since 81 but you want a 85 or later (30 spline) because the bugs were out of it by then. The

700R4 will save you some fuel and not just because of OD but because of the locking torque converter that was never offered on a THM400. The 700R4 became a 4L60 around 92 when they added a electronic valve body to it (it is same tranny otherwise) and the 4L80 is basically a THM 400 with a OD added to it and the first 3 gears even have same ratios. .

----------------- TheSnoMan.com

Are you sure a 700R4 is basically a TH350?

Al

The 700R4 and the 4L60 are virtually the same, it might be modeled somewhat after a 350 but no interchangeability of internals. The TH400 also know as the 3L80 (meaning 3 = 3 spd. L = Longitudaly (sp) mounted 80 = 8000 GVW they added overdrive and became the 4L80E 4 + 4 spd ...... all the rest stays the same except for the E is electronic... a lot of the clutches and seal drums etc... are the same. (p.s. don't know why they call it 8000 gvw and put it in 15000 gvw truck) Also someone mentioned to get the 30 spline 700r4 but I'm almost positive by memory that the 350 was a 27 spline and you'll need to change the input in the transfer case... If you need to do that you can get the parts for it thru Rockford Gear. We had to do that when we went from 5 speed to 700R4 which also brings you to what you said about you'd like to go with a manual... might have to change the input in the transfer case to do that too...