Below is the response I got from someone advertising a 'slant 6' carb on craigslist when I asked what year/Holley #:

"I think it's from 1970. It's a holley with 6260 2 and 3646 stamped on the side."

Anybody know?

Well, I've got an OEM Holley parts manual right here, and it identifies the number 6260-2 as a Holley model 1920, from a '68-'71 Chrysler , 198-225 c.i. engine, auto choke, all transmissions vehicle. It has no reference to the number 3646.
Sounds like the seller is trying to be a square-shooter. Just hope it's a rebuildable core.

Good luck.....Roger

That's the casting number found on the body, common to the 1920s.

Thanks for the replies.

The guy seems to be a v8 guy unloading his /6, 1bbl & 7-1/4 rear stuff that came with/in his project cars.

He's only looking for $20. If nothing else it can be a parts donor.