ok well I have a 7 1/4 out of a 65 barracuda sitting in the way here but i haven't popped it open ,but it did work when we drove the car on the trailer 4 years ago. I"m going to be selling off every thing here I don't need to get a 3:91 sure grip soon assome 1 throws up 1 at a reasonable price got a few hits yesterday . if you have a 3:91sure grip in the way holler. I"ll pop my 7 1/4 open tommoro or Monday get back to me by a pm K . it wasin a 3 speed on the tree 65 barracuda if you know off hand if that will work or not it could save me some time .