4l80e Overdrive planetary thrust bearing failure

[shootracing22]

My 2003 completely stock 4l80e quit making line pressure and I noticed it starting to slip in 2nd gear and the TCC slips when locking. When I tore into it I found that the overdrive planetary and the forward clutch assembly was damaged due to what apprears to be a thrust bearing failure. But I am not sure what caused this to happen maybe a lubrication problem or possibly a bad bearing due to rust since the transmission sat a long time before being used. Just want to do all I can do to prevent it from reoccurring. I am wanting to build this transmission to hold big power so I have recently ordered a stage 5 kit from Jakes Performance, plan to rollerize the rear case, run a triple disc converter and run tight end clearances. From what I have read the input shaft splines on the overdrive planetary is not a common failure but since mine is damaged I am thinking about going with a TCS or PATC overdrive planet with a hardened input billet spline hub. This is my first 4l80e build and I feel I have gained a lot of knowledge from forums like this one. Any tips or ideas that caused this issue are greatly appreciated!