5.5 x 15" - 901.361.012.04
6 x 15" - 901.361.012.03 => "911 R wheel"
6 x 15" - 901.361.012.06 => "deep six", similar to the "911 R" wheel
6 x 15" - 911.361.020.00 => later version, flat
6 x 15" - 911.361.020.10 => later version, flat (from 1/75 on)
the one on the foto looks like the "deep six" to me