Thanks! yes, I've spent lots of time looking at that site and have seen the very nice 49ers pictures (an am intrigued by the green handled 498 - but that's a different matter).
It is not clear in the picture (at least to me) which sheaths go with which knives.
Like I said, I have a 498 and a 499. The 498 blade is both wider and longer than the 499 blade, and correspondingly, the 498 sheath is larger than the 499 sheath.
I was kind of suspicious though that the 498 and the 497 might use the same sheath - and that the 491 and the 499 might also use the same sheath - as the 497/8 have larger blades than the 491/9
i didn't know if anyone happened to have all four and could verify or refute this.