OK, I measured some bars. I thought our 62 Jetfire had a different bar but turns out that the thickness is all the same for the 61-62 other than police. The part I find funny is that all three of my 62 Jetfire have an identification nub on one end and the Cutlass version does not have this. Not sure the reason for this. I am going to use the 15/16 bar on our 62 4 speed car and see if i can tell a difference. I am a purist but this is easy to switch back. I did have to get bushings for the 64-72 cars to get a hole large enough.
61-62 bars are 13/16
61-62 Police car bars are 7/8
63 f-85 and Cutlass are 7/8
63 Jetfire and Convertible are 15/16