GM 350THM transmission

350 THM

Used 1969-80. The 1981-86 version was called 350C and had an electronically controlled lock-up torque converter. From 1980-84 there was a 250C with an adjustable band for 2nd gear.

There were MANY versions of these transmissions and were used in various GM models.

It had an aluminum case. Pan shape is similar to 200 THM, but is not embossed "METRIC". It has a modulator and there is a removable extension housing. With the exception of the manual lever seal and the rear seal and bushing NONE of the parts for this transmission are interchangeable with the 200 THM.

This transmission was an hydraulically controlled 3 speed.

Top cooler line is the cooler return line.

Band adjustments:
Intermediate = not adjustable (350)
Intermediate = 3 turns (250)
Reverse = not used

Gear Ratios:
2.52:1 1st gear
1.52:1 2nd gear
1.00:1 3rd gear
1.93:1 reverse