I thought the 2 halves of the TREK-22 stock were split right down the middle, all the way around. But where the Picatinny rail is on top, instead of being split down the middle, there's only a mold parting line in the plastic. The 2 halves are actually joined together on the right side of the pic rail, right where the angle of the dovetail comes back to the vertical part of the rib. There's just barely enough room there to mount an optic on the rail and not have to remove it every time you take the stock off to clean the gun or work on it. I took mine all apart and replaced the tight-fitting solid steel bolt stop pin with a blue rubber recoil buffer that I'm pretty sure was an old Wilson Combat Shok-Buff brand. They don't make them anymore, but I have a black one made by someone else in my 10/22.
I put just a drop of E6000 Industrial Adhesive on all 10 hex nuts to try to keep them from falling out the next time I split the stock. And I used a few drops to try to keep the rear QD sling cup in the left side of the stock too, because it falls out really easily when the stock halves are separated. E6000 is made by the same company that makes Goop and a bunch of other stuff too. My friend likes E6000 for some things because it has a small hole in the nozzle, instead of a toothpaste-like tube with a big hole that Goop uses because it's more viscous. I took the green ERGO ladder-style rail covers off my VRF14 and replaced them with black rail covers. And I put the OD Green rail covers on my OD Green Trek-22, from the red dot mount, all the way to the front. I still need to buy a front QD sling swivel mount to go in the M-LOK slots on one side, and a flashlight mount for the Desert Camouflage Olight Warrior Mini 2 flashlight that was on my 20" AR for the other side. And I think I'll put an OD Green M-LOK AFG - Angled Fore Grip on it too, about as far forward as possible. That should be about it for this gun, but I still need to buy a Pic rail for my 10/22 so I can mount a scope.
I put the Vortex SPARC II that was on my MechTech CCU on this gun, and the SIG Romeo MSR will go on the CCU. The Romeo MSR only has a 20mm objective lens, and the SPARC II is 22mm. I figured I could use the extra 10% lens size on this gun, and a little less on the CCU with a 3X magnifier will still work. I don't want to weigh this gun down with a magnifier when the 10/22 will probably have a 3-9x or 4x scope on it. I also have a 2.5x scope I think I bought for a shotgun. This mount is slightly lower than the mount the red dot was on, which I put back on the CCU. It's like the difference between an absolute co-witness and a lower 1/3 co-witness, so I would have to use an adaptor plate to get the height on the CCU to match the magnifier with this mount. But the slightly lower height seems like it will work okay on the Trek-22. If not, I can start stacking adaptors to make it as tall as I want to.
https://eclecticproducts.com/product/e6000-industrial-adhesive/ https://magpul.com/m-lok-afg-angled-fore-grip.html?mp_global_color=193