@rubberfingers
Some have a diamond shape on the pulley end but they all take the same pulley - worth noting so that when setting up you get it the right way round. Best thing thing to do would be to feel up the port with the exhaust off.
I have both a 3SH TDR125 and a 3XP 200WR if you need any info - both engines are in one piece though so cant comment on the internals right now 😉