Rear differential w/LSD rebuild options

So I am getting a little frustrated with the available options I have and I need some advice. I am going to rebuild/upgrade my rear differential LSD clutch assembly. I have done some research and found almost ZERO rebuild kits for my rear differential. I'm not too concerned with replacing the bearings and seals since none are making noise or leaking and they are pretty simple to replace. However I have found that my LSD rear differential is not quite up to par as I would like it to be. I can be on loose gravel and the rear LSD diff acts like an open diff setup. The LSD function seems to not work at all. I tried putting in new fluid with the friction modifier additive and no change. There is not any excessive debris or burnt smell either. The only thing I can find is to install factory plates and clutches, shim the carrier assembly, set backlash and reinstall. I was hoping to find maybe a tougher spring, stronger clutches, ETC... I dont want to go all out with a whole locker (spartan, detroit, arb, ETC) setup, I just want to improve on the factory setup if possible.
Any advice on what's the best root to take would be much appreciated.
-Thanks