Hi it´s Stefan in Sweden
Is it any one out there who can tell me how I can find out what engine and gear box my 68 Coupe came with from the factory.No info on the gas tank. Sad
Sincerely Stefan

Stefan, welcome to C3VR
Here's some info that might help you. This is from the corvette black book, relative to engine suffix codes located in the factory stamping. Hope this helps!!

HE: 327ci, 300hp (manual transmission)
HO: 327ci, 300hp (automatic transmission)
HP: 327ci, 350hp (air conditioning, manual transmission, power steering)
HT: 327ci, 350hp (manual transmission)
IL: 427ci, 390hp (manual transmission)
IM: 427ci, 400hp (manual transmission)
IO: 427ci, 400hp (automatic transmission)
IQ: 427ci, 390hp (automatic transmission)
IR: 427ci, 435hp (manual transmission)
IT: 427ci, 430hp (L88) (aluminum heads, manual transmission)
IU: 427ci, 435hp (aluminum heads, manual transmission)

Hi Stephan

No, it is not 100 % possible to find out without the build sheet ( tank sticker ).
You can estimate more or less by looking at options, like tach red line, 1 or 2 fuel lines , manual or auto trans, rear end ratio , aft sway bar or none , radiator with expansion tank or none , ignition
( transistorized ), and much more.
Looking at all this will tell you if it was a big block, or hi performance small block.
But as sayed B4, only a estimation.
Like my 68 with a non numbers matching big block engine was 99 % a 427/435 HP L71 car.
If I have the cash one of this days, I might get a correct block and tripower setup to correctly restore the car. Until then, I enjoy the non numbers matching big block with the mechanical HOLLEY as is.

Good luck. Gunther