I've done a lot of comparing back and forth and it seriously looks like this tank is an M60, first production model. It has the hull of the M60s, with a turret and tracks that look like an M48's. I can't find a model online of an early model M60, just the A1 onwards, which have very different turrets.

Am I going to have to buy an M48 and an M60 and kit bash? That wouldn't be the worst thing ever.