Back wheels resisting/locking up intermittently on bumps

So I was driving down a long dirt road with lots of water bars and rocks and started to feel like the truck was braking itself every once in a while while going over bumps. On the way back down, I actually seen the driver side rear tire lock up completely for a second and then release. Not sure if the passenger did the same. Tough problem to recreate as it is super intermittent. Once I hit pavement the problem is gone. Any idea on what might be causing this? I recently changed front brakes (don’t think this has anything to do with it) dropped my rear axle to replace my leaf springs. I’m assuming I would be hearing metal on metal noise if it was related to bad u joints or bad rear diff? Thinking of pulling the drums off and replacing rear brakes and then looking for anything that might be a give away.
Thanks
Here’s a pic of the truck, picked it up for 2k, been adding things here and there and doing maintenance trying to make it my off-road rig.

 

Traction control?

 

So I thought about that but I don’t have any buttons in the inside of the cab that indicate I have TC. But I do believe that the rear diff has LSD on the sticker

 

Where you on the brake at all when the rear locked up?

 

2006 would still be old style hydraulic LSD. I think it was 08+ that got the electronic LSD which would have a button.

I thought my 05 had a stability control button down low even though it had the hydraulic LSD but maybe I remember it wrong. Sold that truck like 10 years ago.

 

@545 no I wasn’t on the brakes.

does anyone know if there’s any way I can disable TC by disconnecting any wires since there’s no button? My ABS and brake light are already on I think because of bad sensors but I’m not really interested in having ABS anyways lol

 

Your parking brake cables maybe seized, check if your shoes are dragging by seeing if they warm up driving around.

 

Truck looks pretty modified, maybe the parking brake cables can't handle the added suspension travel and could be pulling and therefore braking? Haven't really looked at how the cables are laid out and mounted so maybe this isn't possible

 

Ok, been doing a little more research on Tacoma world. So I’ve also recently went up to a bigger tire size. I’ve seen people who do have the button will have to reset their VSC through the obd2 plug when going up in tire size. Is this something that would still apply to me even if the truck does not have the Trac control button? Or do I just not have traction control at all and my computer should never be telling my brakes to self apply? If so that should narrow my problem down to just a brake issue. Thanks (also looks like there’s plenty of slack in my e brake line where it shouldn’t be too tight)