Good question I'm not aware of anything other than the badging and the limited production numbers. Also they are all painted silver.

This has been discussed on here before and I think Randall, the owner of 2 Silver Arrow's, has documented everything that came with car.
You will have to use the Search Engine and try and find it. I can't remember everything that came on or with it.
Basically there is no mechanical differences over a regular 1999, but there are a lot of cosmetic's and goodies that came with the car along with special paint.
The headrests are embroidered with the Silver Arrow logo. Does yours have them installed.?

The Silver Arrow (SA) was a regular production fully loaded Riviera except of the 1956 1999 Rivieras built in 1999 only the 200 SAs were painted Sterling Silver Metallic.
The SA goodies were made by an aftermarket company and sent to the dealership in a box in the trunk for the dealer to install.
There was an instruction sheet that came with it telling them the placement of all of the badges.
The quarter panel “Riviera” emblem was supposed to be removed and the SA emblem put in its place.
The dash panel emblem, the number plate, was supposed to be placed on the knee bolster below the dash panel between the glove compartment door and the vent. One of the ones that I have was put in the wrong place like yours is but I didn't move it, I figured it would just mess up the dash panel if I did.
Along with the badges there were embroidered headrests and floor mats, a SA car cover, a sterling silver pin, a leather owners manual cover, the two key rings, and a SA booklet kind of explaining the history of the SA.
That’s all I can remember right now but I think that’s it.
Great find and great buy!

There is a man that is in the BCA and the ROA that is keeping a Registry on them, I think he has over 50 of them on it at this time, if interested let me know and I can give you his contact info.

RickW,

Silver Arrow is embossed into the headrest. Thats really weird how they are all different because of possible dealership installation errors.

Wow, amazing you found this for $1500. When I was looking for my Riv umpteen years ago SAs were nowhere to be found, except for one at $40K, and that was out of the question for me.

That's a great deal! I got my 1997 for $1700 or something. Had lower miles than yours but still.

Congrats and have fun with it!