I remember reading a long time ago about a SU-45 that was build ontop a tractor that was armored. It had a single weapon 45mm tank gun model 38. It was build as a stopgap vehicle in the summer/autum of 1941 and last ones destroyed in the sring of 1942.
Link:
http://rkkaww2.armchairgeneral.com/g...d_Tractors.htm
EDITED:
Find this on Wikipedia on it as by the name of "KhTZ-16", but I have seen it called SU-45 too. Anyhow this is probably a defferent vehicle altogether...
Wikipedia link:
http://en.wikipedia.org/wiki/KhTZ-16