Everything seems to be matching up numbers-wise on my '78 Z28, however I am confused a bit on the engine code suffix: V0223CHS 18N572537 The engine build date (0223-Feb. 23) is a month prior to the cowl tag production date of 03C (third week of March). That's the way it should be according to my research. I've got the PZ off the rear axle, which would indicate 3:73 posi that the Z28 had in 1978. The thing confusing me is I have a Borg Warner 4 speed manual transmission in the car. All the sites I looked at says the engine suffix of CHS should go with an automatic transmission. Stegmiller's site says for the suffix: Z28 CHS th Which means to me it's the numbers matching engine for the Z28, but what does th stand for on that site? I assumed the m/t would be for manual tranny. Could this car have been switched from an auto to manual tranny? I am the 3rd owner so I don't know the complete history of the car, but that never came up in the discussion of its history. Thanks for any help on this.