Gotcha. I assume you are running TT F/R in something like a D1? (I have a D1 with a TT rear, 4 pin up front-that likewise I installed myself).
What you may well find, assuming you haven't spent much time wheeling the 3/4 series Discos, is that these will behave differently than a lighter truck with a traction aid. The locker could be useful, and should be incorporated into the search of course, but-in my experience-won't overcome some of the challenges that come with the weight of the truck.
Quite frankly single biggest thing you are going to want to do, especially in a 4, is find a way to get appropriate tires on there. If we were talking LR3 I'd suggest going to far as the V6 brake swap and 17's with MTs. LR4's make that a bit more challenging since I don't think you can get there from here.
That isn't to say that these trucks can't handle long protracted mud like where you wheel-just that in the grand scheme of things their weight will conspire and as you likely know better than I given your conditions, tires are the key along with HP to clear them. The computers of the truck will get you very close to acting like an LSD even in a non HD truck-in my experience, comparing platforms.
r-
Ray
I had a D1 with a rear locker. My current ride is a Jeep Liberty with lift and LSD's that I plan on keeping. I stay out of the bottomless pits around here. The rain here leaves our hill climbs with deep long blown out rain ruts that are a challenge even in dry conditions. I got to drive a LR4 and was surprised that such a capable off roader could have such nice road manners. I think its a unique vehicle in that regard.