The trans itself is pretty strong, will go for plenty of miles.
Just has some quirks to it. Can handle stock power levels with ease (if you arent beating the **** outta it everyday), just once alot is added, parts start to wear faster and tend to break from being too weak for whats needed.
A leading cause of failure on the GXP's is heat, the aluminum block of the LS4 always heats the trans up faster and cooks the fluid faster than the v6 cars. Coolers are a good thing to invest in.
The TCC might be your issue like you are saying, you can check out Triple Edge Performance and see if it has anything to add to possible causes.
