There was a wheel warehouse somewhere down there that had all MC's discontinued wheels, I bought one last year from them for my trailer fairly inexpensively. I'll try and find my paperwork with the name of the place and get it to you. The wheel I got was the same style as yours only 15" ( single axle) but the warehouse had both.
2003 Prostar 197 TT #56
2007 Chev Avalanche LTZ