I just finished upgrading my Delta 50-850, with Gary MacIntyer's cyclone. (Ebay Item# 270423194251) After speaking with Gary , at length, I bit off on the unit for $227.75 deliverd to my home. I used the motor and impeller from the 850 and this is what I came up with.
This thing is AWSOME!!!!! My CFM is throught he roof and I'm all plumbed with 6" HVAC 30ga. pipe. I am convinced this is the best money I've spent in a long time. It has done everything, and MORE that Gary said it would.
The third picture is of the carcass of the 850. I have that, and several pieces of 4" PVC pipe, and several pieces of 4" black flex tubing that I no longer need. If there is anyone that would like to trade me something equally useless to them, and are willing to pick it up in Metro Chicagoland, just PM me so we can work it out. Of course I'll clean it up before tranport.
Ken
BTW- I am not affiliated with the seller or the product in any form. Just happy with the purchase.