I have went through a couple of trannys in the last 2 years with two different trucks. My tranny in my 98 12 valve wast just plain wore out at 240K. I bought the truck with 235K on the ticker, I started modding it and at 240, she gave way. I went with a single disk torque converter, upgraded the valve body, and installed a TC (torque converter) lockup switch. With what I done to the engine it was probably only pushing 300 hp at the flywheel. I ended up selling that truck because I needed a crew cab.
Bought an 03 crew cab dually that I have now. it has the Edge box with upgraded injectors ( I was told they were 100 sticks, not exactly sure). Anyway, the owner told me he had never had his box above 1 when I bought it from him. It didn't take me long when the Devil on my left shoulder began saying "Crank it UP" :hehe:, so i did (no higher than 3), then one day coming home in a heavy snow storm, yep, it crapped out on me :shock:. I made it about 2K miles once I started playing around with it before the tranny went.
So, I installed the same setup I done in my 98. Ran the Edge box to 5 and toasted that tranny in one month. :shock::shock:
I now have a 3 disk, billet input, upgraded flexplate, flywheel, valvebody, and TC toggle. I haul heavy from time to time with my truck so I needed something that would be reliable and hold the loads and hold together when the Devil says "Crank it UP" again :hehe:
All of that being said, I can't tell you which manufacturer to use, I went with Dacco for the TC and Dunrite for the valvebody and had a highly reputable shop put it all together for me with a warranty.
the one thing that I would recommend is getting a TC toggle switch installed, I love mine when I am going down hill, it holds the load back so much better.
Sorry for the longwinded description. Just thought I would tell you my tranny woes to maybe help you make the best decision for yourself. :thumbsup: