The M60 MBT has a multi-threaded upgrade program.
From earliest to last, skipping a few minor ones.
The M60A1 (1962) starts the ball rolling with the M68 gun and cupola for the M85 MG. AVDS-1790-2A diesel, CD-850-5.
Then there's M60A1 AOS (1972) which gets stabilization.
We're skipping over the M60A2...
Then M60A1 RISE (1975) which upgrades the engine, transmission (AVDS-1790-2A diesel and CD-850-6) and electrical system. Oh, and adds AOS if it didn't already have it.
M60A1 RISE+ (1978) adds passive IR, an NBC system, better radios, ditches the M73 for the M240 and smoke dischargers.
M60A3 Passive (1978) is like a RISE+ with a better engine and transmission (AVDS-1790-2D, CD-850-6A), upgraded fire control computer wind-sensor, laser rangefinder and better night vision gear. Some tanks were upgraded, some were new build to this standard.
M60A3 TTS (1978) is an M60A3 Passive with a thermal gun sight.
M60A1 RISE Passive (1980) gets the engine and transmission upgrade from the M60A3 Passive, plus a kevlar spall liner, better night vision for the driver, deep fording kit and mounts for reactive armor. Another way of saying it, it's an M60A3 passive without the fire control and ranging upgrades that can partially submerge.
The Army and Marines made the same upgrades through M60A1 RISE+. The Marines didn't spend their budget to shoot better or see better.
I totally forgot the split between M60A1 RISE Passive and M60A3 TTS.


















