Mikester- great video. But my experience was different. Maybe he used the correct stock spring for the Chevelle and then that one-at-the-spring-equals-two-at-the-body formula works. But if you were putting a big block in a G-body, or some other non-existent combination, you are back to try-it-and-see-then-cut-1/4 coil. OP- I do know that when ordering springs from ESPO the rep asks you every relevant question because even AC will make a difference. Also long ago a spring shop fixed me up with new front springs for a '68 LeSabre. The guy wire brushed the end of a coil and came up with a code number. Using that number he selected springs that would give me 2" more lift. Sometimes it pays to talk to a pro.