You should have no trouble finding another original Old Timer in carbon steel. The small stockman knives were quite common and aren't premium-priced like many Old Timer models.
Sorry, but I disagrees with the Case suggestions. Their quality is so hit-or-miss that I cannot recommend them sight unseen. And someone accustomed to Schrade's 1095 carbon steel probably isn't going to be happy with Case's CV, and certainly not their stainless.
Boker has a nice selection of models in carbon steel. Might look at some of those. Much higher level of fit-and-finish than Case, for about the same price.
I wonder if Canal Street has any small stockman patterns, or much in carbon steel? Their quality recently is excellent. I'd be happy with their D2 or other above-average steel choices.
Queen's D2 is nice also. Of course it won't patina like 1095, but the usability is excellent. Most of their smaller knives tend to be "QueenSteel," a lower-end stainless.
If the price doesn't scare you off, there's no one making a higher quality knife than Great Eastern right now. I'm almost certain they don't have a small stockman though. Check out the White Owl and Pony Jack for GEC pocketknives that aren't heavy or bulky.