Taken from Tiger's readme from his Allied fieldguns mod:
bmps 4370-4377 (17-lber AT gun)
bmps 4400-4409 (Allied AA guns. 40mm, 90mm Bofors)
bmps 4220-4225 (76mm AT gun, 105 howizter, 25-lber)
bmp 4018 (gun carriage stops)
bmps 4380-4381 (57mm, 6-lber)
I think using a 1 before these numbers will give you the winter BMP numbers.