[ QUOTE ]
Also noticed there is one extra digit in there..
T12223S 
The only codes the 1968 L-36 Biscayne used were:
*IB w/TH400 Police
*IC w/3 speed Police
*IE & IH w/Manual
*IJ & IS w/TH400
[/ QUOTE ]
Yes that is what I mean. Maybe the engine code on this engine is "3S". This still doesn't match the accepted GM codes for this engine in this car... I still can't find a reference anywhere to this engine code. When I last looked at the block (a while ago now) I'm pretty sure it said this same stamping, I wasn't too concerned except that it match, and Didn't pay much attention beyond the date portion at that time, maybe there is more stamping after that part?, but then there would be way to many digits, and this is the correct number of digits the way it stands...
I wonder if any ex-Tonawanda employees lurk here and might shed some light......