Sweet big ol' knives you got there. The sheath for that custom job looks really cool. Looks like something a tribesman made after consuming a few peyote buttons.
The only really "big" knife in my meager collection at the moment is a 1980 model (date code letter "D") W49 Western Bowie. I believe it was made in Colorado - before Coleman bought out the company. Occasionally our guys in Vietnam used to buy this particular model at the PX and carry them in the field. This one was supposedly carried by an advisor.
Bowie Knife - Vietnam War Weapons
That's mine on the far left: