muzzleflash88 hi
firstly yes i think that you can use t-34 tracks for your su-100.
i did a search on hannants and came up with a whole bunch of stuff
; now i know you're stateside right? but this should still give you an idea what's out there, so all you have to do is get the stuff from your LHS or, dare i say it, evil
bay!!
hope this helps.
regards,
nick