I have an older Case slimline trapper, brown delrin scales. The main blade has patina, marked CASE XX/ USA/.. (two dots) not stainless. The other is a long spey type blade marked 62048SP and clearly different (stainless) than the main. I always thought it was a modified knife,but the fit is good, so maybe not? Is this a production knife or a home brew mod??
It's probably legit, the pattern number is correct anyway - is it only marked 62048SP or does it have an SSP stamp also?