99 Zaskar ID Help. Possible custom?

Hi, I need help from you Zaskar gurus out there. I bought a 99 14.5 Zaskar frame (not LE) and am wondering if it's a factory custom frame. I did identify it as a 99 Zaskar by the flat cap, serial number (0499), easton stamp on the top tube, and CNC head tube.

It was advertised as NOS (never built) which I was skeptical of because of the color which is Gloss Black with silver/white/grey decals. According to the 99 GT catalog, it was only available in Hot mango, and ball burnished. I've heard/read that GT did some custom order stuff from time to time, so I'm wondering if it's possible this could be a factory custom one-off.

The frame has all the correct year original decals in the correct spots, I believe there is clearcoat over them, but I'm not sure. The chainstay has no indication of chainslap and has the protector, and there are no marks in the aluminum at the dropouts. The inner BB shell and head tube look pristine. The H2O bosses have no indication of masking, etc. I understand that marks can be sanded and filled out, but if it is a repaint, someone did an exceptionally nice job. Did GT prime the frames before paint? There is a hint of what looks like red oxide primer around the BB shell faces

The finish is smooth & glossy, with little to no orange peel. The seller didn't have any history on the frame, but said it kicked around his shop for most of the decade, and it does show some age & minor rash. The decals have some minor cracking/chipping, there are 1or 2 tiny chips/scuffs/very light scratches. So the finish looks age appropriate. Other than that it's pretty immaculate. Like I said, I'm skeptical. I'm just wondering if anyone out there can confirm either way. The serial # is 04990615
I appreciate any input, Thanks!