George,I have at least a 1/2 dz. swivel bolt,they are all the same.I think the reason the one slot looks wider is that the end on the long one is about 1/16 " narrower with thinner sides and when slot was punched it bulged the middle where as the other has more material and didn't bulge.I put the one with the bulged sides in the vise,gave it a little pressure and the slot width is now identical.I have a friend in TX that has a 70 Hemi Cuda,talked to him last night and he confirmed the longer one is the same as on his car so evidently the longer is the 70 /71.Don't see any reason for change,carb spacing is the same,throttle linkage the same and once adjusted,over all length is the same.The only reason I can see for a longer rod end is if the connecting rod was shortened.