anyone have info on when the vehicle numbers stopped being put on the schuerzen of StuG IV (if they ever did have lurid red numbers on them)? wondering if I could do mine (Italy 1944) with 1 panel from another vehicle- was thinking one that had originally been plain dunkelgelb with red/white numbers that my vehicle used but painted brown/green over the numbers....

would a front line unit be painting over "liberated" panels or just having them as was?

The 3 digit number ID'd the vehicle within the unit. This was used until the end of the war. You could use a piece of schurzen from a KO'd vehicle.
An option is to apply the new number over the old one.

now theres a possibility - will have to think on that.. i am missing 1 middle (battle damage) so would have say 2 "Old" digits on the panel, fully weathered then overspray of camouflage then reapplication of 2 "new" numbers (then weathered