We currently purchase a "500 lbs 3 wheel rope pulley hoist" and mount the blocks directly to a 1 inch diameter tube. See attached picture. These are imported from China by our supplier I think. We are looking for a source for the components for these small 3 wheel blocks (or for a similar sized 'In Line' pulley block). Each block uses: (see attached image with ruler (available by email)). 4 - 85mm x 38mm x 1mm(?) steel. (prefer structural aluminum) 3 - 35mm x 6mm sheaves (nylon, black plastic, hard rubbery black material) 6 - 14mm x 7 spacers (nylon, black plastic, hard rubbery black material) 3 - 6mm X 40mm bolts with lock nuts for half 3 - 6mm X 63mm bolts with lock nuts for half 1 - 1mm steel hooks for half We only need 100 sets until we get into production, then 1000/month. Thank you, Jim xxxxx