I picked up a 72 lemans 2.79 rear end cheap and want to swap it into my 66 gto to see if I like the shorter gear better than my 3.55. The springs for the 66 have the bolt down bottoms and the 72 is a cup. Are the tops the same between the 66 and the 72? It looks like the 72 has a pigtail top looking at the insulators in Ames and the 66 has an open top the same as the rest of the spring. The 66 springs will fit around the cups, but its not a snug fit and doesn't look too good. Advice?