After having my drivers' side window thump to the bottom of the door cavity one freezing night, I checked it out and found out that somebody has mauled the bottom slide channel around with pliers in an attempt to make the regulator lug run in the channel without a wire clip. It must have been run like that a few years, because the lug, which is supposed to be circular, has flattened out at the top to a misshapen oval. From my research, the clip looks pretty much the same as an early Bug one, but I'm worried the wear on the lug is going to make it drop the clip and I'm back where I started.
Can't find any T3-specific replacement regulators for sale, or even any broken early Type 1 regulators that I can filch a lug from. But the regulator looks damn similar to VW Part 111 837 502D - the 55-64 Bug regulator, which I reckon I probably can get. Has anybody used these things in place of a Type 3 regulator, or know if it could work?

Just for the record, I still don't know the answer. Somebody on The Samba thought the Bug regulator arm might be shorter - unknown if that'd affect the window travel. I got a mid-60s used one from Boris and cut and welded its arm and lug to my 1971 winder mechanism to keep the same winder shaft. Works fine.