I bought one just recently to go with my Case Sodbuster JR. I'm not a fan of carrying larger knives in my pocket and wanted a sheath to carry the knife as I worked outside. After reading the reviews on Amazon.com, it seemed like a safe bet with the Sodbuster. My Sodbuster fits snuggly and shows no sign of coming loose or falling out. Overall, the Sodbuster maybe somewhat thicker than your Trapper, though. I seem to remember some of the reviews on Amazon saying the sheath was too loose for a Trapper or Stockman. That's just from memory, though.
The fit and finish are OK on the sheath. Although it does its job, it's not an impressive sheath by any means. I've noticed it's a snug fit to get on some belts. So, be sure you also consider what width of belt you wear in addition to the size of knife you intend to carry.
Hope that helps some!