If you look at the casing it should push in modulator valve or another way to tell is the vent but I cant be 100% sure if the '70 had the vent/umbrella on the top of the casing but pretty sure it didn't. The man should be able to tell what year it is. I heard from an older friend of mine that has been around that it is possible to put extra band in 3rd to promote a stronger/firmer shift to third by not slipping as it applies pressure to the bands. I love my C-4 after the top loader swap, more street performance.Good Luck!