I'm just saying I have read a number of guys that drive their cars a lot/hard complaining, FWIW. I also know a local guy using it in a 67 and not having trouble. But he's a cruiser. The trunk pans are different early vs later 2nd gens. The filler necks are different for the 3 'sub-gens'. I know the necks are longer in the later models, I didn't think about it and installed a 79 tank in my 77 that a friend had and the neck kept the license plate from closing properly. So I take from that the 74-77 neck will be too short in a 78-81.