Vintage Rolex 15505

[submerged007]

Hi!

I am new to Rolex. Presently I have only one Rolex, a Two tone Blue sub which I bought new a few months ago. I love it.

I would like to buy a vintage Rolex and came across the 15505 at a dealers website. While I like the look of it, I am a bit confused about this watch. The description says:

"MODEL: 15505 S/NO: "864xxxx" Year 1984. Chronometer in 18K yellow gold filled on stainless steel base Rolex case 34mm, originally made by Rolex Company, original Rolex dial with index bar markers. Fitted with brand new leather strap with Rolex buckle, automatic movement 3035 movement, rolling date model, acrylic crystal"

and here is the photo (hope it is ok to post it here):


My main confusion(s) is/are:
Is it an ORIGINAL watch or a modified one?

Is it a collectible model?

If not, any suggestions to a vintage Rolex around this price range?

Thanks!