Anybody know what the differences are between the early RS6 main radiator and the later one's? There doesn't seem to be any aftermarket options for the later one. Part number is 4B3121251F versus a D for the earlier one.

There seems to be an extra inlet for the transmission fluid possibly? Wonder if there is a way to bypass this and use an earlier Rad as the price difference is significant. ~$1100 vs $300.