Complex sentence: The latest version of the Patton was the M60A3 variant that entered service in 1978 two years prior to the introduction of the M1 Abrams that replaced it over a ten year period (Some M48A5 models also served alongside them both as well into the 80s).
Split into simpler sentences: The latest version of the Patton was the M60A3 variant that entered service in 1978. In 1980 the M1 Abrams was introduced, which would replace the Patton tank series over a ten year period (Some M48A5 models also served alongside them both as well into the 1980s).