For sale is a Lincoln LN 25 Wirefeed. This one has "the works": it has a gas solenoid and a gas hookup, and it also has a welding current contactor -- so the tip of your welding gun is only hot when welding. This is worth hundreds of dollars alone and is a great safety feature. When I purchased this wire feed, the MIG gun on it was in poor shape, so I replaced it with a Tweco compatible, USA made welding gun. This one goes to 0.045". The welder has feed rolls that are made for 5/64" wire, so you will need to replace those with feed rolls suitable for the wire that you will be feeding.
I verified operation of this wire feed by connecting it across the arc, and found that the feed mechanism is working, and the contactor clicks. While the wire feed is obviously used, I do not see any issues with it. I will accept a return for a full refund, but you will pay all shipping costs.