5508 Sub with military provenance

[cajuntiger]

Hi all,
Ive been away from the forums for a few years and out of touch with the current state of vintage Rolex, so looking for some advice on a friend's watch.

She inherited her Dad's 5508 Rolex last year. He served in the US Navy on a submarine and bought the watch right after Graduation from the Naval Academy around 1958-59. She literally found the watch in his sock drawer with boxes of his military medals after he passed away last year. She recalls that he wore it all the time.

She has some photos of him wearing the watch while in uniform, unfortunately they aren't the clearest images of the watch itself...but she does recall that he always wore it backwards on his left wrist.

The watch has some issue...when she brought it to me to evaluate it wasn't running and the crystal was badly scratched...it was very difficult to see the dial condition. I used some poly watch and was able to see that the dial is in remarkable condition...but then checked it with a black light and geiger counter. The hands and dial all glow evenly, but the geiger registers nothing. Yet the dial appears correct for serial is 400176, which puts the date of manufacture around 1958. But then I removed the case back and this is where it gets interesting...the Caseback is dated III.66. I posted about this earlier in the year, but adding some additional info.

My observations:
1- The dial is a gilt dial that appears correct for 1958 (not a typical service dial), but it has Tritium or similar lume. Why?
2- The case back is dated 1966 and only has one service mark
3- The case and caliber 1530 movement appear original
4- The bezel is original, but the insert is later.
5- The hands appear to be later hands from 60's...possible replaced at same service?

Regarding #1 and #2...im assuming that her Dad brought the watch to be serviced in 1966 and for some reason the dial was replaced, but a correct gilt spare dial was still in stock so it was lumed with the current tritium. This would explain the case back being changed as well. Alternately he could have sent it to Rolex with the request to have the radioactive dial replaced, this is a reasonable possibility as he was hoping to transition to a nuclear sub...regardless this is all speculation as she cant find any service paperwork or receipts.

Any advice or comments on the dial would be appreciated...has anyone seen a service dial like this on a 5508?