I'm planning on a diorama set during the battle of Berlin but am stumped by a couple fundamental aspects: 1-Is a 1943 model T-34 (hex-bolt turret, no cupola) suitable? 2-What is the possibility of an Opel Blitz remaining in panzer gray to this late in the war? And 3-what sort of weathering should I aim for? I was thinking traces of dry mud and light-coloured dust.
All your knowledge would be greatly appreciated! Thanks!

Not an expert but will try to help:
1.- While I can not rule it out, all photos I have seen are of the T-34/85 variant so I would say it was quite unlikely to find a 1943 model.

2.- Yes. There is a footage from the surrender at Czechoslovakia showing dark grey trucks (and without paint scratches, by the way).

3.- Berlin was heavily bombed so I would say there would be lots of rubble and concrete dust all around

Thank you! I had a feeling the T-34 would be too early. luckily my LHS has a t-34 85 in stock and the price tag should keep it there for a while.

The soil in the area is sandy but there would be lots of dust. Lack of it is what always damages the credibility of urban ruins in dioramas for me. Fortunately there are plenty of colour photos of European cities after bombing so those will give you an idea of how monochromatic it looks.

Thank you! Looking at pictures I do see lots of light dust and plenty of rubble, so I'll be sure to include this.