The current trans in the 72 GMC is a TH350, with the 400 engine and 4:10 gears and no 
OD the truck is not much for gas mileage, the goal is to install a updated trans and transfer case
into the truck to gain a little more gas mileage and still retain the power to tow heavy loads
if needed, left out of OD the new trans will have the same final ratio as the TH350 the strength 
of the 700R4 is also as good as the TH350.

Below is the trans out of my rusty but trusty 86 Suburban 1/2 ton 4x4 I had it for 12 years and
the trans performed flawlessly and was in perfect working order when removed. 

It has the factory 6 lug heave duty torque converter.



Where it will be installed.

Old trans on the right new (used) on the left, I am told the new having the aluminum transfer case
will weigh about 200 lbs less than the old.

Here are some installed pictures, I had to make some 1-1/4" thick spacers to go between the 
cross member and frame, once I get this thing back on the road I will test for vibration if 
any is present will investigate drive shaft angle and shim the trans as required.

See the silver band on the front drive shaft slip yoke? That is the old wear mark when it was 
installed on the Suburban in the future the front shaft will be lengthen to ensure it has enough  
travel to be used off road, since this truck is rarely used off road and the 4WD used in snow
on pavement changing the shaft length is not a priority.

The old speaker magnet is something I use on all my trans, rather than throw them away I stick
them on the trans pan to catch any metal that may be in the oil :-) The front drive shaft is now a 
little short the new trans setup must be longer the blue arrow is the wear spot with the stock 
trans setup I will look into a longer front shaft when I get the rear shaft balanced.


The transfer case shifter from the 86 Suburban dropped right into the factory hole for the old 
shifter, only a minor adjustment was required to the linkage to make it work.


The stock Suburban drive shaft was shortened 3.5" and a conversion U joint was installed
at the axle end of the shaft to mate up with 3/4 ton rear axle.