Seeking fresh eyes for an analysis of this ca. 1981 Sub 16800

[Nobody.Move]

I’ve always been partial to the cleaner look of the 5513 Subs, but recently I’ve become intrigued by the matte dial 16800. This watch is currently in my possession, pending purchase. I’m hoping some 16800 owners and experts will analyse these eleven images and offer their opinion on the authenticity and condition of the watch.

Here are the details: 7.2 mil serial number; no box/papers; head only; apparently one owner; crystal has some small chips at the top edge btw. the 12 and 1 hour markers; bezel is very difficult to rotate and it moves in both rotations, smoothly, i.e. without a clicking sound; weight seems consistent with two 5513s I own; case back exterior has “machined,”circular marks in the center; date numbers are serif style; watch has not been opened so the interior caseback text and watch movement are unknown to me.
Thank you in advance for all those who elect to view these pics* and offer their honest opinion, it’s very much appreciated.

*Unfortunately a few images show slight camera movement. Images have been cropped to show details, but no filters were used.

[The_Walrus]

I think it is a nice honest and genuine piece.
Nice dial and hands and fat case.
I would view the movement though before putting your money down.
You'd want to be sure there is not corrosion going on in there.

[Kyle13]

Originally Posted by The_Walrus

I think it is a nice honest and genuine piece.
Nice dial and hands and fat case.
I would view the movement though before putting your money down.
You'd want to be sure there is not corrosion going on in there.

+1 on having the movement checked out.

[Nobody.Move]

Thanks George and Kyle13 for your input, it's very much appreciated.
fyi: I definitely intend on having it opened up...looking forward to it!