RE: DAK panzer IV
Those are 2 different Tiger tanks. All of the 501 Tigers in Tunisia were the initial production versions with many detail differences from regular production tanks which include the 504 Tanks.
The Turret Numbers of the 1 Kp. of the 501st were white outline. The 2 Kp. were white outline with black in the center and they also put the number on the rear bin on at least some tanks.
The 504ths 131 Tiger is the one at Bovington. It's been said these numbers were originally red but others now say black.
The 501st took delivery of their Tigers between August and December '42. The 11 Tiger tanks of the 504th were delivered to the unit on 28 February '43.