That looks like a FM H10-44.
Hobbyline did a drive for them in 1957! Most recently I believe Walthers Proto did one a few years ago.
Walthers had one long before the Proto version (Roco drive I believe). I think even Athearn had a blue box H12-44.
But I am guessing rather than finding a chassis, it will be cheaper & easier to buy a whole new unit of the exact brand and swapping the bodies out.