[JLHarper]

Welcome Al;

Some good info on PY on these cars, they have been discussed from time to time.

I own a 70 455 RA auto myself, and couple of other guys do as well, with and without the RA , a rare option.

The GTO Assoc of Americas GTO Illustrated Identification Guide by Eric White is a VG reference book for basic codes and part numbers.
It lists each year and has codes/part nus. for alternators, exh mans., rears, trans, carbs, distis, wheel codes, raditaor tag codes, and much more...option codes too.

Performance Years sells them. and they list each model by year and have codes and part number for much of the stamped or dated parts.

DISTI #: 1112012 and many I see (or own) are dated around 9L xx I think or DEC, xx of 1969.

ALTERNATOR: 1100704 with standard w/o A/C 37 amp
1100700 with A/C Rear, other options 55 amp
1100895 with A/C and heated glass rear window 61 amp

EXHAUST MANFIOLDS: there was a change over, (two diff nus.) so I was told, so will let someone else post this...may depend on your build date.

Does your car have a twelve bolt rear?

Couple of others on here that are also (like OPH) well versed on these cars and one member: Held For Ransom is collecting data on these.

Jeff