Hello folks - need a little help with Campy compatibility craziness. Somewhere I've read that some later campy cogs are reverse compatible with 7 and/or 8 speed freehub bodies. I need replacement cogs for a 7 speed setup. The hub is first generation Chorus/record (removable chrome lube ring on center of hub, unlike Athena.) Freehub is 7 speed, fitted with lettered cogs, evenly spaced splines. Just wanted to ask: Did 7 and 8 speed use the same cogs? Are 9 speed cogs NOT reverse compatible with the 7,8 speed splines? Thought I read somewhere they are. Can I mount an 8 or 9 speed freehub body on this hub? I realize a 9 speed would eliminate the possibility of using my 7 speed shifters and an 8 speed would necessitate a spacer in place of the last cog. Thanks much for your help. I miss freewheels - Just screw one with the right spacing on.
Btw, I'm not against non-campy cog replacements

They have the same spline pattern, with the 7 speed body 5mm shorter.

They're not backwards compatible. 9 speed splines have a smaller inside diameter so there's enough surface area to work with aluminum freehubs that are lighter but softer.

I suspect you could swap an axle and free hub together, in 8 or 9 speed - the C-Record forgings were used through 1999 or 2000 although Chorus/Record switched to the over-sized aluminum axle design at that time with no parts compatibility. You could probably find a used hub and swap insides selling off the '7 speed' hub you're no longer using.

For the axle swap to work you need a cup-and-cone axle (flats on NDS cone and lock nut), not one of the 9 speed cartridge bearing hubs.

If you're picky about cog selection, you want to go that route - I updated my 1996 Chorus hubs to 9 cogs with new freehubs around 2000 when Campagnolo discontinued 13-14-15-16-17-18-19-21 8 cogs which was my favorite.

Thanks, Drew - very helpful. I'll probably look for a new 8sp cassette or a used axle to swap, though the race on the drive side of my hub is less than perfect. Still feels smooth to the fingers after new bearings and grease, no grooves, but has some light pitting. I don't think you can get the replacement races anywhere. Best I've seen for a new 8 speed cassette is about $50. Maybe I'll stumble over a good condition used one. Would upgrade to 9 speed hub, but I'd like to avoid changing shifters. I may just rebuild with another 7 or 8 speed hub, selling off a freehub body.