Plastic / Composite Blower Pulley

I'm looking for distributors ( wholesale ) of 6" - 14" plastic/ composite pulleys. On a number of the new evaporator coolers I have installed, the pulleys ( Chicago die cast ), both the motor and blower pulleys have been manufactured faulty. They are die cast. The issue with the motor pulleys ( vaiable pitch ) is/ was : bent, threads misaligned, set screw loose in bore ( these are supposedly brand new in a sealed kit bag supplied with cooler.

I now use Browning pulleys and belts.

I found one company on line, Fenner drives. They have 8.25 - 10.98 ( 4L ) , I saw them on grainger. The issue with the blower pulley has been out of round, resulting in blower and motor bearing wear. I have had to buy 5 pulleys at a time, at local retail stores, check them in the shop and had to return 3-4.

The Trade store is 45 miles away. Most of them only sell the same pulley. R. E. Michael carries Congress ( die cast )

Any help with supplier lists is appreciated.