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Pionier44
i just spray the inside the same as the outside dark yellow, but thats on a 251Ausf D
it might have been different at the start of the war but i cant answer that
they had rubber road wheels on the 251s through out the war but they started using all metal tracks near the end of the war
try this site http://www.geocities.com/MotorCity/Pit/3515/251/index.htm
heres a picture of one ive done (long time ago)