It'll be cool to pull things together from the various threads.
FYI, the 12PM and 12ZM featured the "T-62" threaded rim TurboHead first, then the 2.5" short rim TurboHead once the T-62 had run out. I'm not convinced they ever had the 3" T-Series Extended Range TurboHead as stock.
The 6PT and...
I'm not sure how it's different to normal Sxx remote tape switches? All U06 feature the S06. I suppose they're hard to find now-a-days given how many years ago the Classic WeaponLight components were replaced by Millennium components like the XM tailcap. Great to see it in use!
SureFire have used A and B etc to indicate different versions of model. See the X-type handhelds for example. Perhaps if they offer a version of the LX2U with a clickie type tailcap it'll be the B version...
One may expect the two versions of the proposed EB1 to also have such designations
Those are tricky for me to answer and I doubt I could be definitive like I get the impression you're after. I'd have to spend quite a bit of time researching and I'm not sure who at SureFire is still in a position to dig around their records. Why is it important? It may help get some answers...
It is an obvious difference - the Z59 is type II Black anodised whereas the U2's TailCap is type III "Hard" anodised.
I'd suggest trying to contact SureFire first before resorting to getting a Z59 yourself.
I suppose that frequent removal of the Lamp Assembly would cause some wear of the 'location shaft' - I've not noticed this obviously happening to any of my TurboHeads though.
Key things to remember is that it is almost impossible to clear reflectors once they are dirty so if you're going to...
The M6 (no such model as "M-6"), has one o-ring on the bezel-end of the body.
One may assume that the apparent location for an additional o-ring may be so that SureFire can supply small quantities of deep depth-rated Millennium-Series models to specialist military units.
The N62 is black without etched marking.
The MN60 and MN61 are black with etched markings.
The old versions of the MN20 and MN21 were purple and grey if memory serves