[Harp-L] Shure 545 question

[nonidesign@xxxxxxx]

pistol style Shure 545 lovers....

I've seen several Shure 545 pistol mics but they've all had various different model numbers, Unidyne serial designations, etc.on them.

I was wondering if there are certain general differences in the sound of 545 pistol mics. 
By that I don't mean the difference between the sound of a 545 as opposed to a crystal MC151 or black label CR element. What I mean is do different model designations of pistol 545s have differences in their sound relative to each other by model #?

Are there "preferred" models for these mics (in the same way that certain black face vs silver face Fender amps of the same model are considered and compared to each other)?