1900 Brake Caliper Carrier Sliding Bolts - Three Styles?

[stark 0]

I've stripped a few sets of 1900 front brake calipers and found that the sliding bolts that the calipers bolt onto on the caliper carriers vary. There are three styles of varying diameters / styles as shown in the photo below.

 

There doesn't seem to be any logic as to which style is used and when as some had two of one style fitted, one each of another etc. Even the top bolt from the left carrier was different to the top bolt in the right carrier... Unless these have been messed around with before I ever got them, can anyone please explain the logic / what should fit where? I know some have rubber sleeves (to reduce vibration!?) but the carriers themselves also vary in internal diameter so only some sliding bolts fit some carriers...!!!

 

Any help would be greatly appreciated!