This group is for everyone who like tanks, sci-fi tanks, real tanks, funny tanks, you can put here tank mods, tank maps, simply everything with straps, armor and gun :D
CATTB or Component Advanced Technology Test Bed is a experimental model with a 140 mm smoothbore gun, heavily armored turret and upgraded hull based on the M1's chassis. It had a mechanical loading system in turret bustle, a new engine and probably other upgrades, never fielded. The tank went trials in 1987-1988. Current status unknown.
Found it when I was poking around.