Maybe I should have given some context on this. The truck in question has 345,000 miles on it. I limped it very hard a few times at around 270,000 miles on a race tune and have dealt with a wounded transmission ever since but on a lower power level of course. This truck will realistically never be taken past 450 HP again. It's just not worth the risk of depleting my bank account at this mileage and age.
Anyway it seems like there are countless ways to address the C3 clutch. My thoughts are the stock clutches are more than sufficient for me, I just need to up the plate count and increase the squeeze on the clutches. I should have just bought the TTS kit years ago and had it on hand for when I finally had the time and place to work on the transmission. The Allison is an easy trans to work on but I don't have enough knowledge with it to know what parts can be mixed and matched to make something really strong using stock components. I would prefer to buy a "kit" that includes all the pieces needed to open the trans up and address the C3 clutch if that helps narrow down the suggestions any. Thanks for the input so far guys.
Edit: My parts transmission is a 2008 Allison 1000 with what was said to be 200,000 miles on it. It has a flawless set of C1, C2 and C5 clutches in it. The C3 and C4 clutches are slightly discolored and have a few hot spots on the steels. I know the 6 speed trans addressed the balance piston issue in the C2 clutch that plagued the 5 speeds. I believe the C4 pack should be good as new in my 5 speed Allison as it's only used in 2nd gear in that application. I'm planning on taking two and making one good transmission with minimal parts being purchased. I know everyone on the Internet says you can't or shouldn't with an Allison but if 3 of the 5 clutch packs look like new and will hold all the power I will ever put through them and with room to spare I'm going to run them.