Hasselblad 503 cx

Hi all,
I wonder if you can help me to figure out the differences between two versions of 503 cx bodies. One has old stile of the shutter release button with the window indicator and the second has a new type of the release button and no window.
Cheers

Are you perhaps confusing the 503cxi and 503cx?

The 503cx did not have the the new release button or GMS system and had the old style bottom plate.
The new style release came first with the 501C in 1994, so there was an overlap, but that did not have the GMS but did have the new style bottom plate.
The 503cxi was from 1994 with new style release, no indicator, the bottom plate was the new style and winder compatibility was added but no GMS which came with the 503cw.

If you are looking at specific bodies the year date code would help clarify and the body code applied to late models would confirm, the two numbers on the serial that precede the date code letters are model codes.
The 503cxi is number 11 thus: 11EC39805 (1995 model) again AFAIK the 503cx did not have the preceding number code just the serial beginning with the date code letters, like this: RE1430205 (1989 model)

I therefore think you are looking not at two 503cx models but a 503cx and a 503cxi.