Thanks Joe K - it does appear that there were 5 different bezel variants. The first of which is consistent with the British Military example that is being discussed.

 

Correct that this late type bezel didn't have any lume on the 5 min. markers. Like mine below and like the spare one I have for a 166.024.
And actually I think there were 7 different bezels on the 2.gen SM300 in total. The 2 extra's besides the above are subtle variations of the 2 latest ones (A and D).

 

Very nice Military example Kox

For the last Bezel with a round luminous triangle and no luminous index at 5 points,i've nerver seen one before.

 

The bezel without luminous at 5 indexs has been produced with a big luminous triangle on the bezel at 12 o'clock

 

Thanks.
Here's another one below.
Basically the difference on the "A" types are that the font/lume is more bold/fat, but font type is the same and yes, the shape of the 12 o'clock triangle. Sharp, narrow or broad or rounded. All have no lume on 5 min markers.
Btw, the type looks precisely the same as the sm120 bezel on the 166.073 (the successor to the 166.024), but is NOT the same. There are different dimensions on the back. Both in black and blue.

 

This 2 bezel are very similar.
Amazing seamaster 120

 

An essential for anyone making a first foray in to the 300 world -
http://forum.tz-uk.com/showthread.p...mega-Seamaster-300-including-Military-watches

 

Great thread!

I'll throw mine into the hat as well