Ralph. You can get these from summit. Heavy duty S clip and carbon fiber clutch kit. Works amazingly great
I'm not sure why you would insist that the TL works amazingly great. I know you aren't much of a drag racer so maybe that's it? On the street a lot of things work "amazingly great". I've had people swear to me that they have a TL when they don't. They seem to think that just because the car spins both tires most of the time, it must be a TL. I know you don't fit into that category, but the point is valid - on the street it doesn't take much to get both tires spinning. A completely worn out TL will spin both tires on the street basically all the time.
I chuckle lots of times when people install an Auburn and then complain that their car won't spin the tires anymore. It makes a difference if you have a solid performing differential as opposed to one that mostly works. Just because both tires spin doesn't mean they both spin at the same speed. Traction is always improved when the diff is solid. How do you know yours is solid? The best hint is to take it to the track and have someone watch you do burnouts from behind. You would be amazed how many people say "but I just rebuilt the TL?!?!"
Which unit you get should be determined by how you drive and what is important to you. If you street drive only, don't mind the occasional rebuild, and want something that is mostly unnoticeable most of the time, a TL is a good option.
A more aggressive diff like the Auburn will bind on tight corners and will tend to push in corners unless you break the rear end loose. It will make noise occasionally and it will generally let you know that it's back there until it too wears out.
If you want something that is completely invisible in all types of normal driving yet hooks up BEST in corners and coming out of them, then a Torsen or Tru Trac is the only answer. They are not junk, but they do wear out and they aren't as strong for drag racing. The difference between a Torsen/TT and a TL in terms of wearing out is that the TL has replaceable parts whereas when you wear out a Torsen/TT you are looking at scattered parts. Drag racing will shorten the life of a gear type differential as this is just not the purpose it was designed for. If you don't launch real hard it will be fine, but if you planning to do 5000rpm clutch dumps, then it's not the way to go.
Another thing that people forget about is the unique shock loads that the IRS sees. If you have a 5spd then wheel hop becomes an important consideration. Be aware that the tighter the diff is, the less likely the car is to wheel hop. Since the IRS is, well, independent, you can very easily put all the load on one side of the car which will result in over compression of that side bushings and exaggerate wheel hop. On the other hand, if the diff is very tight (like a Detroit Locker) then it will force both wheels to put the same forward force on the suspension and will actually very significantly reduce your tendency to wheel hop. An Auburn Pro does this pretty well too.
I'm just saying that there are reasons to choose one over the other and being aware of what the benefits of each are can help you make the right choice. I don't personally like dealing with diff fluid all that much so I prefer to do it once and do it right.