GM Automatic Transmissions

The TH-350 is a medium duty trans built from 1969 to 1989. It was used behind 6 cylinder and small V8s engines and was designed to handle up to 425 pound feet of torque. The TH-375B is a heavy duty 350. The 700R4 was put behind 455 engines among others. The 700-R4 in 1992 became the 4L60. Later the E was added to mean electronic shifting. For those who are wondering...

The 4 is 4 speed, L is longitude, (rear wheel) and 60 is a rating for strength. The higher the rating the stronger the trans. The 3L80 is a renamed 400. The 3L80HD is a 475. The 4L80 is a 400 trans with OD, and the 4L80E is electronic.

The 200-4R and the 700-R4 have overdrive planetary gears and use a lock up converter. The 200-4R and the 700-R4 are very close in torque rate. The 200-4R has a deeper OD and deeper 1st, 2nd, and 3rd gears. Anyone thinking of buying a 200-4R, be sure it says METRIC on the pan. If it doesn't, you're getting a plain 200. Also, in case someone wanted to know, a "T" in the trans designation means transaxle. (Front wheel).