I am looking at a '68 Camaro SS convertible possibly an L89. What are the things that I can check to see if it's real? I know about 12 bolt rear end, something about the leaf springs? , big block heater core?(What is a big block heater core?), 3/8" fuel line?, no fuel line return, no AC. Anyone know of anything else that I can check?
Thanks

There were 272 L89 cars made in 68 model year, so the one you're looking at would be very, very rare. 68s are also the most difficult to confirm without original documentation.

Start with the basics. VIN must start with 12467, not 12367.

According to both the White Book and CRG, "MT" is the only suffix for a 68 L89 engine. So, the pad stamp should be TxxxxMT, and be a real stamp (not restamped). Also, if it's real, the partial VIN stamp should match.

L78/L89 only available with M-21 or M-22 4-speed, possibly M13 HD 3-speed or M20 (I see conflicting data on M-20. No automatic (Not available). The big block manual trans crossmember has an angular side on the cutout for the bolts (when viewed from underneath).

Must be a multi-leaf 12-bolt, but there were 7 gear ratio choices ranging from 3.07 up to 4.88. The AMA specs I got from Chevy say it should be 5-leaf springs.

Big block heater cores have fittings in the center of the heater box cover vs. coming through the firewall next to the trans tunnel opening on a small block car.

Yes, it must have the 3/8" fuel line. The 1/4" vent/return line is a 69 Q-jet thing only, so it's no help on a 68.

Yes, no AC.

http://www.camaros.org/diffs68.shtml

Again, unless the owner has been living under a very large rock, or you are looking at a $50K plus car, it's probably not an SS L89. Unless the code stamping and VIN stamping are real and match, and/or the original sales paperwork, POP, etc. are with it, 68s are very hard to prove.

High redline tach also.

That's right. Redline at 6K RPM.

Thanks for all your help. If you think of any thing else, please pass it along.
Thanks