OK, I figured it out at camaros.net and camaros.org. Dunno if anybody's interested, but the axel tube code--PA0629G2--translates to a 3.08 non-posi, 10-bolt rear end made on June 29 at the Chevy Gear & Axel plant, Shift 1. The differential cast cose--F23 7--means June 23, 1967.

Now I need to decide if I want to convert this rearend to posi or not. How does this rearend compare to a '67 Pontiac 10-bolt?