Do you have any pix of the windshield? I don't have any idea what a 1999 Crestliner Sportfish 1750 windshield looks like. But I suspect it's NOT a Crestliner specific windshield. It's like made by a vendor that supplies several boat makers. Check @ ebay. And you can try Lanier Marine in Georgia, but via the phone & internet many have said they are difficult to deal w/.
If you haven't tried them already, you can try these salvage places:
Salvage yards
Are you missing (or it was all damaged) the ENTIRE starboard side windshield?
Or just the 'glass', you have the frame?
Your best bet is to find something that works and can be made to fit and look 'right' whether it's an exact match to what you have now. Which means an ALL new windshield, not just the starboard side.
BTW: It makes you
vintage, and possibly not in the good way like boats, cars & wine
good luck in your hunt