Abu Garcia sent me the part, it appears to be an original stock part, wow, just what I needed (they call it a "clutch" now). I'm impressed that they still carry parts for such old reels. Anyway, installing it was not as bad as I'd been led to believe. I did a few practice runs with the broken part and then went on to fix my reel. She's a beauty, can't wait to try it out.
So my 6000 still has all original parts, even the drag. After soaking the old disks in mineral spirits a few hours, they work quite well, smooth and strong. It's going to be interesting fishing with a 3 point something to 1 gear ratio though,
I think it's 3.5:1 ?
Kudos to Abu Garcia!