The following is directly from Mike Eagleshield at CZ-USA, as the result of a phone conversation and email question. This information was received by email, today (06/07/2005) My additions/explanations are included in [brackets]:
1. The dovetail is the same on the 85 Combat [and the 75B], save for the milled away portion to the rear. It will accept all 75 sights.
2. The LPA low profile adjustable [i.e., the standard adjustable that comes on the 85 Combat and Kadet Kit] can be fitted to any current 75 by milling away the [the raised rib on the] slide, to the rear of the dovetail.
3. We now offer an LPA high profile adjustable fiber optic sight set(front & rear) that will fit all current 75's for $89.95.
4. We also offer a fiber optic front sight that will replace all current 75 front sights for $29.95. There is no fiber optic rear sight [sold by itself].
5. We currently get our Tritium sights from PT and also Meprolight (when we can get them).
6. The low wedge [Novak-like] rear sight on the PCRs is a factory design and will fit any current 75, with metal [the raised rib] removed forward of the dovetail.
7. All current 75 based pistols will have the same front sight and 6 possible different height rear sights, to correct for elevation.
Note: The earliest 75's also had a narrower rear sight dovetail and rear sights for it are no longer available. The good news is it can always be opened up to take any current 75 rear sight.
With regard to the parts availability for the the original 75 (pre-b) pistols, Mike wrote:
The original pistol uses the same basic parts as the current 75, save for the safety, safety detent and front sight (stake on).
I currently have run out of original safeties and front sights, but does have the safety detents in stock.
Mike's statement above was a general one, as weknow, too, of some other differences with hammers, which have varying widths, and firing pins and firing pin springs.