The Jadgpanzer Hetzer was built on the Czech LT vz38 tank, or as it was called in German use the PzKpfw 38(t). The Germans "aquired" them from the Czechs after they didnt need them anymore. The Germans were glad to have them as in some ways they were better than the frontline models they had at the time, though very quickly the PzKpfw 38(t) became obsolete with the introduction of newer units.
I actually think the horse drawn wagon should be the primary German resupply GV, as their army, even up to the very end of the war, was predominantly non-mechanized, they moved with beasts of burden.
But since AH doesnt have the horse properly modeled I guess the M3 will do as a substitute.