5513 bracelet, what is correct?

[Phi.H]

Hi all from a newbie.
I currently own a 1980 5513 Submariner but I've been questioned a couple of times about the bracelet. Mine has a 78360 bracelet without the oyster-lock. Now I've been told that this is the bracelet fitted to the GMT of the same period but NOT the Sub. My old friend Barry had a 5513 of a similar vintage that he sold 4-5 years ago and that had the same bracelet as mine. Since he'd been questioned about it a few times too, he did a little investigating and quickly unearthed several 5513s with the same bracelet.
It seems a bit odd to me that there are quite a few out there fitted with this type of bracelet. Firstly, it would take one heck of a lot of damage to render a bracelet unserviceable (and you'd wonder why the watch wasn't damaged too if things were that bad). Secondly, assuming the bracelet was so badly damaged that it had to be replaced why replace it with a GMT bracelet rather than the original oyster-lock ??, both types would have been available at the time.

I can only think of two possible scenarios:
1) did Rolex actually sell some 5513 Subs in the early 1980's that were fitted with this bracelet as standard?

or

2) was this a popular option for some owners who, for some reason, didn't like the oyster-lock and weren't using the watch as a diving watch so changed the bracelet?

I'm currently looking for a buyer in the For Sale section so I'd like to know in order to satisfy my curiosity over a question that's been bugging me for years and to have a definitive answer if a buyer asks me about the bracelet.

Any input would be much appreciated, thanks, Phil.