Thanks guys for the comments.
DML's T34/85 supplied the hull, with one set of wheels cut out, the commanders cupola and the gun barrel. Sheet plastic to smooth out the front and side armor. Squared exhaust from a late Panther and side skirts from the E-10. The main gun mantle is from a M1A1.
The wheels are from the T-34/85 kit.
The basic story is that when the Russians captured an E-10 and/or Hetzer, they wanted to test the value of a high-velocity gun on a low profile - high speed chassis. Using shortened extra T-34 hulls and the 85mm gun.........
The project did not last long with development of the SU-100.