Are All /6 distributors the same ?

Why would my distributor cap not work or fit another /6 distributor ?
Is there 2 different cap or is there 2 different distributors ?
Rotor fits real REAL tight on the new one (I have to force it down in place) (compared to the old one) and the cap seems to be to tight for the new one, The distributor I have been running the cap just about falls right on and the rotor falls right on by it's self and almost loose (wiggly) .

Is there 2 different cap/distributor size ? Year models ?


Thank you for all the tech help, I am dumb founded and have dun this 10 dozen times and never ran in to this before.. :oops: