Check with Arrowcraft, I believe they are in Michigan. Don't bother with all the other aftermarket or distributors. Call up to Michigan and talk with the boss lady. I bought my wheel spacers, wheels from her and this lady KNOWS HER STUFF!! Axle widths, frame widths, wheel spacing the whole nine yards. As a mechanic I was very impressed with her knowledge!
http://www.arrowcraft.com/You will not be disappointed. I bought my stuff around 6 years ago and quick shipping, everything I needed and it all fit like a glove. She will steer you away from aluminum as she has seen the ones that did not survive. My adapters were steel and had not one single day of trouble from them in 6 years.