A redesign of http://fc05.deviantart.net/fs43/i/2.....contrail09.jpg

The T.4 "Verdist" (Defender) is a medium tank used by Callentine Forces from 801 AW onwards. It uses a 155mm rifled cannon, and its large-bore barrel can also fire specially-encased TOW or laser-guided anti-tank missiles.

And for your queries, yes, I based this thing off the M551 Sheridan, although this was not designed to be air-droppable.