The SU-76 used a longer hull , 6 road wheels as opposed to 5 on the T-70 . It would be easy enough for Rubicon to make a generic hull / wheel , track sprue ( both lower hulls , 6 pairs wheels , extra track links ) that could be used with either the upper hull sprue of a SU-76 or T-70 kit . Many of their Sherman's have universal sprues of which you only use a few bits depending on the version your building ( turrets , fenders , etc ) I hope they think about it ,as I really like both those vehicles