hey mate! see this http://wiki.r31skylineclub.com/index.php?title=Alternator. There are three kinds of alternator on the R31, Mitsubishi, Hitachi, and Bosch. There may also be two flavours of Bosch. This page has photos of the all alloy cased Bosch (as opposed to the partially plastic cased Bosch - which auto sparkies hate because it's hard to rebuild).