The original X-1100 automatic transmission was developed by Allison Transmission (a Division of General Motors) in the 1970s and installed in both competing prototypes of the XM1 MBT built by Chrysler Defense and General Motors.
The Chrysler Defense XM1 was subsequently selected and production of the X-1100-3B transmission commenced in September 1979. The configuration developed for the heavier M1A1 MBT was introduced into production in April 1985 and incorporates changes that further improve the efficiency and reliability of the transmission.