Smokey, good info on tank codes!... Somewhere I have notes on a few tank codes too but ever since I moved I have no idea where they are? Not sure if you have the info in your notes but It would be helpful to put foot notes after the tank codes as to application. I marked the 'XJ' as I know it's for a Chevelle. I'll also add (I'm 99% sure on this) that the fill tanks for Camaro & Firebird are the only ones that have a 45 degree slant for the radiator cap, every other GM model I have seen has a 90 degree corner. For example, that's why a 4 core manual fill tank on a 1970 Chevelle is coded 'XJ" and the 4 core manual fill tank on a 1970 Camaro is coded 'XY'. However, both 1970 Camaro & Chevelle used the same 4 core 'IF' tank on the drivers side. So if someone has a fill tank with a 45 degree slant on the fill tank, odds are it came from a Camaro or Firebird. On the picture I show above in post #19 with the 'LR' coded tag from Eric's L78, I have a picture of his original window sticker from this car and it shows the 'VO1' heavy duty cooling option. So 'LR' is a 4 row core radiator for manual trans.