By the age of your machine, I am betting you have 10" rear wheels with a 4/4 bolt pattern. Spacers for that machine will be hard to find. A lot of the early machines had 10" rear wheels with a 4 on 4" bolt pattern. The front wheels are 12" with the more common 4 on 156mm bolt pattern. the bolt pattern for the rears is not common and I doubt that you will find any used ones.
I found a new set on Ebay that are listed for about $45 a pair. I would link it if I knew how. I did a search for "Polaris 325 magnum spacer" and after some scrolling there they were. Probably the only way you will find them. Unless you know someone who does CAD and can design them then get a machine shop to make them.
Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
Polaris Hand warmers, Mirrors.
Hers: 2019 Sportsman 450. 26" Bear Claw HTRs on Moose 427X Wheels.
2007 Sportsman 500 EFI, Polaris Winch, 25" Bear Claws QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2017 Polaris Ranger 1000XP - Roof and front glass
2018 Kawasaki KLR650
2001 Magnum 325 Warn winch and Moose 60" plow-Sent to Daughter and Son-In-Law since his blew up
SOLD 2004 Sportsman 600 Twin