Dan, this topic has shown up a few times before but I'm having trouble even finding my own post ...
Short answer: Yes, but be prepared to pay well. Barry Jensen / Jencon Bits of Pieces is the only gunsmith I know of right now who is building these, from scratch / 1.25" blanks. If you look at the barrel lug, that part that descends and has the feed ramp on the chamber side, there are a lot of angles and measurements to get exactly right in a mirror image. I've heard various prices, most over $300. The nice tight bushing and good barrel your Dad's 39-2 has now are the source of that accuracy (a retired shooting instructor put a 1/2" group of 5 shots right on the bullseye with mine, I know what you mean). A new barrel may mean that doesn't happen any more, though Barry's are very good. I haven't fired one of his guns yet. Maybe someone here has one. It takes a while to get done.
Joe Dlask apparently used to do these.
BarSto used to make these barrels, so there are some around in 106+ mm, but they will be in other guns and you would have to buy a whole gun (restricted, so not such good deals) to get one. BarSto won't even talk to you about these (well, maybe you know someone there).
There were a crate of "spare parts" extended / threaded barrels made by the Smith & Wesson factory for the US Special Forces. Some still show up in guns, with an added slide lock lever, called the "Hush Puppy" variation. Even if the crate is found, it's unlikely we'll ever see any barrels from it here. They might be long melted.
There is always M D Charleton, who at least used to be the Smith & Wesson distributor. Has anybody heard from them lately?
Smith & Wesson had a bit of variation in manufacture, but I don't think the 39-2 had 105mm (you need 105mm+ -- the headspace gap is usually enough to add the +) barrels like some other models have.
Beware of "barrel lengthening". Others may want to comment here.
Quite a few other CGN members have these barrels and various experiences they might share again. If you buy "just a barrel" you'll need the bushing too, or someone who has a supply of unmodified bushings and can fit the barrel for you.
In good condition, the 39 and 39-2 are really, really nice pistols. Worth saving.