That's some great info there. So basically, for whatever reason, they changed the stamping for the axle but not for the trans. Yet on A12 cars only, the 603 does means Hemi 4spd since that's the only thing they came with. It does and it doesn't, sorta. You'd think they would just of stamped the one number to a 5 and the tag would make sense since they restamped the rear anyway..sorta?

I just bought an A12 clone Runner, and I know it actually has an 18 spline trans in there, since that's how he had it built and has the receipts and pics to prove it. It's a Lynch Road car too and is a factory 4spd car to boot. I was under the impression, since I've been on the hunt for a real A12 Bee project, that the 603 meant Hemi 4spd but didn't realize 605 was the code. Glad I kept this post as a reference. Nice to learn new things about stuff you thought you already know. Now I know, and knowing is half the battle! Great info guys, thanks!

Cheers