I have an RPO code K05, after looking it up and it says block heater. But i cannot find it on the car.

Are you the original owner of the car? If not perhaps the previous owner had coolant seepage issues or whatever and simply replaced it with a freeze plug in the block. Or if it was pre-owned maybe the engine itself has been replaced. Or (say it ain't so) maybe the factory simply screwed up and omitted it. At any rate the grounded 110V electrical cord used with block heaters usually isn't all that hard to spot if indeed you have one.

2004 Bonne SLE
1971 Chevelle SS

i bought the car from an elderly couple. They bought the car new and it only had 80,000 miles on it, so im sure the engine is original. ill have to take another look.

Could have the block heater element but the cord is missing.