4L70E problems. Again!

[zach_carver]

Ok guys I need some help. I have a 65 C10 with LS2 and 4l70e from a trailblazer SS. I'm having terrible trans problems. I have pulled and reinstalled 3 times in a month. I'll start from the beginning, had trans rebuilt before installing in truck had 100k miles on it. Headed on a trip with it and I lost 3rd and 4th gears. Removed trans builder said 3/4 gear clutches gone again. He fixed it, reinstalled drove 60 miles died again. This time it was as he said "welded togther". He was unable to get planetarys apart. So tired of fooling with what I thought was a crappy builder I call GM and order a new crate 4l70e. Well now I've driven it 3 4 days solid great running shifts beautifully. Noticed today trans was starting to get a little hot after a pretty good little trip it was 199. Then it started slipping, flailing shifts. I'm afraid I'm gonna smoke this new trans. My truck has a cooler thru the aluminum champion radiator only. And I'm using rubber high pressure trans cooler lines. Any help/insight is greatly appreciated.