I removed the flange with a combination of a cutting torch and a 4.5 inch metal cut-off disc on my grinder. The spot welds were ground out with a grinder disc. I elected not to drill out the spot welds as I did not want to go back and refill the holes.
The seat is a bit of a mystery. I cannot identify what it came from as it was a $40 swap meet special. It seems to work fine but I have had to fabriate new risers for it to get the height where I want it. It sure is a heavy sucker. The max width the AD trucks seem to accept is 55 inches. The G-body monte carlos, cutlasses and the like are good seat donors.
