[Karl Bebout]

Tin-Man, The TH400 is a three speed automatic transmission that GM made for about 30 years. The 4L80e is basically the same but has a fourth gear that is a 25% underdrive to reduce engine RPMs when cruising. Hughes is a racing transmission manufacturer in Phx that has been making wonderful transmissions for decades. I went with a manual 4L80e so that I wouldn't need a computer to operate the transmission. I will have to manually shift but I always do that anyway to try to reduce any slippage my 10" torque converter might allow at lower RPM.