on my 1980 olds cutlass calais i found the date code on the front of the engine behind the water pump between the oil fill tube and the sending unit i think. it says 4790 gm is this right and where is the casting no. is it to the left of the oil fill tube behind the ac compressor or behind the alternator? or is it in the back by the dist? i am confused. it is not the original engine just not sure what year. not enough thermo vacumume switches. i thought about bypassing all the vacumme lines and simplifying but i don't think i can out think the gm engineers, the things were there for a reason.