Hi everyone,

New here so apologies if wrong post format etc.

I recently acquired two Mark 4.5's.

Both serials are in 3919XXXX range and are only 18 digits apart. Both come on No. 12 bracelet with 311 end links:





While looking at about 80 other MK4.5's I see all from higher serials come on 1162 bracelets with 11 in circle -- 172 at watch. While I also found two other watches with Omega 311 at watch, No. 12 on bracelet with slightly earlier serials than mine:
https://www.hqmilton.com/timepieces/q05wly02/1975-omega-speedmaster-176.0012-mark-4.5-4094

https://www.yorktime.com/shop/omega-speedmaster-mk-4-5/

Both also use English day name.

Does anyone know if the earliest MK4.5's were all in English day name and all actually came on No.12 bracelet with 311 end links?