RE: Concrete Armor?
Stug often had concrete armour added the Germans didn’t do this with the larger tanks like Panther and Tiger.
Spare tracks were used on many tanks like Panther, Tiger I and Tiger II the British also adorned there Sherman’s with spare tracks one will often find Churchill and Panther tracks added to a Sherman I’m not sure how effective it was it may have been psychological but I don’t recall seeing any pictures of any army’s knocked out tanks with a hole through spare tracks.
The 88L71 from a Tiger also the 75L70 from a Panther at a range of 2000 meters could go through the front and exit the rear of a Sherman thus Germans used HE and delayed the explosion the round would penetrate then explode inside the Sherman, if concrete armour stopped this then it worked well though I don’t this this was widespread, these are the first pictures I have seen, Sherman’s with extra armour, tracks even wood and sand bags I have seen plenty