Engine Identification

[jj498]

My daughter recently bought an 87 Firebird that has been modified. The engine has been swapped to put in a 350 with headers, Eldebrock Performer RPM manifold, and an MSD iginition system. Unfortunately it is pretty much a hack job. I need to figure out how to identify the engine. She thinks the guy told her it was a 75 Chevy 350 but I'm having trouble finding numbers of the block to identify it. Can anybody please help?

[MrPbody]

ON the rear of the block, above the bellhousing flange, there will be a 4-digit alpha-numeric symbol "cast in". It looks like a little "tab" attached with screws, but is integral with the casting. The fiorst letter is the mnth (A-January, etc.). The second and third digit will be the day of the month. The last digit is the last number of the year. Example: D045 would be April 4, 1965, 75 or 85. Logical deduction gets you the rest of the way. There were no 350s in '65. The dipstick goes in on the driver's side on '75s, and on the passenger's side on '85s. '95s might also be "in the mix", but they have a one-piece rear main seal, unlike any of the others.
Check those numbers and get back here.

[jj498]

Thanks for the help. The block code is 3970010 and the date is E 1 5. The head casting number is 333882. The dipstick is on the driver's side and writing this reply. I wish someone had warned me not to have daughters.

[MrPbody]

That would make it a '75, as the '85 would have a passenger's side dipstick. The 882 heads are pretty common for the era. Not a good performance head.