Initially produced in 1966, the M551 was fielded in 1968. 1,562 M551s were built between 1966 and 1970. The Sheridan saw limited action in Vietnam, where many deficiencies were revealed. The missile system was useless against an enemy that barely employed any tanks, though the Sheridan saw a lot of use towards the end of the war because of its mobility.
The Army began to phase out the Sheridan in 1978, although at the time there was no real replacement. Nevertheless the 82nd Airborne were able to keep them on until 1996. The Sheridan was the only air-deployable tank in the inventory. Their units were later upgraded to the M551A1 model, including a thermal sighting system for the commander and gunner.
In the early 1980s the M551A1 was fitted with a visual modification kit to resemble Warsaw Pact vehicles at the National Training Center at Fort Irwin, California. These modified vehicles no longer fulfill that role, having been retired at the end of 2003 and subsequently scrapped or made available as "hard targets" or, in a few cases, as museum pieces. Many were dumped to create artificial reefs.