Not much to add, but I'm finding Case knives to be more-and-more attractive...much to the dismay of my wallet...and my wife...if she knew.

I have several old trappers which my dad had collected, and almost all have been sharpened down to the point that the blades are worn into 'sharpened ice-picks' practically. The old timers got every bit of use from the steel...
Anyway,
AllAbout Pocketknives has this, about the Case #54 pattern:
"This pattern is a 4 1/8" jack knife that is most well known as a trapper.
Case started manufacturing them in the Tested era (1920 - 1940).
The pattern will almost always have two blades; a clip and a spey of the same length.
You may find two variations of clip blades on some older knives. In the mid 60's, the company produced some knives with a narrower clip blade known as a muskrat, or California clip. Knives made with the narrow blade often trade at a higher value.
The frame was changed in the early XX era to one that had longer bolsters (less handle material).
Some trappers that were manufactured in the early XX era (1940 - 1964) were made on the tested frame which has shorter bolsters. These are much more valuable.
"
Image and info from
allaboutpocketknives.com:
http://www.allaboutpocketknives.com/wr_case/patterns_by_number/46_60.php