Decoding Your AMC Trannie
and Rear Axle
by Eddie Stakes
The boat anchor Borg Warner automatics used from 65-71, many people know what I think about them as I have a whole bayou of them behind my house, I think they are junk, but the snapping turtles love them and the EPA don't hassle me because I tell them I am creating habitat for endangered wildlife so I guess it works out. Since I deal with only 68-74 let's concentrate on the automatics used those years. Actually let's narrow it down to 68-72. The big cast iron Borg Warners are M11-B and M-12 Series, used until 1971 on 343, 360, 390, and 401 applications. Starting in 1972, AMC used Torqueflite 727s, a superior trans although some swear by the old Borgs. Why I don't know they are not performance oriented and impossible to find stuff for, and transmission shops will push your car to the back lot while you have to try to find parts for them to even look at it. Enough of that. The 68-71 Borg Warners have a tag attached to the case of the transmission above the pan which carries the vendor number and the AMC Part Number for the application. The six cylinder and smaller V8s (290/304) use the light duty aluminum case transmission, while the 343, 360, 390 and 401 use the cast iron case transmission. One exception is the 68-69 AMX with the 290V8 four barrel which used the big AT. The 72-74 360/401 automatics were Torqueflite 727's with the numbers located on the left side of the pan. The 258-6 (Javelins) and 72-74 Javelin and AMXs with 304V8 used the light duty 904/998 Torqueflite transmissions. *Note that the 904/998 is a awesome "low end" transmission with lots of torque and works great behind a 360 and 401. I have had a 904 behind my 68 Rebel convertible "Machine" with the LAPD policia engine since 1987 and 127,000+ miles.
There is a great transmission list on the AMC Club of Finland's website, and more comprehensive than this by far, but since I only specialze in 68-74 AMX and Javelin this will cover these transmissions and axles. To check out the Finland Transmission site (and be sure to check in and sign their guestbook!) please click here.