I have a 12a and I kind find a date stamp on it anywhere so my question is where would I look and what are the differences between a 79 and an 84 12A if Any?

Forgive me if I'm wrong but doesn;t the '84 have a 13b?

no, only GSL-SE 1st gens came with a 13b. the 12a still came in all the other models.



you can tell if you look at the rotor housings. the older ones, 79-80 will have a square petruding out from the top. the others 81-85 will have a H shape in the same spot.

Thanks for clearing that up for me, and Nick!

thanks that helps a lot

also a couple dumb things ive noticed.



79-80: has the square top rotor housings, also a couple of extra ribs in the casting



80 california only: has an egr valve on the top of the center iron



81 has the H top rotor housings



82 the heater hose nipple on the rear iron goes from a screw in to a pressed in fitting (actually sometime in 81), also gets the shorter oil filter pedestal



83-85: gets the "beehive" oil cooler, heater hose fitting becomes a "T"

And Mike knows his nipples! https://www.nopistons.com/forums/pub...IR#>/smile.gif

the engine I have has the beehive oil cooler with the T fitting so it must be atleast a 83? Are the engine transmission specific or can I just swap the flywheel to make it a 5speed verses the auto trans it had

you can swap flywheels, but why? get a lighter one and it bolts right on. you need a pilot bearing and seal too

I'm lucky to have the 81 and not the 80 LOL