4L80E w/ P1870 code

I searched for old posts with this code but didnt see alot 4L80E's with this problem. My 2001 Silverado 2500 HD has the Trans Component Slip code. It operates perfectly until it reaches a trans temp of
about 150 degrees. Than most of the time it upshifts hard. The local chevy dealer found a service bulletin which stated the torque converter should be replaced. possibly because of a cracked piston/ leak. I took it to two trans repair shops. One ran a diagnostics test and found a TCC slip. 440 RPM @ 50mph. Normal slip is supposed to be 5-30mph. He recommended replacing the torque converter, pump seal, and i think he said the actuator valve too. $1500-2000 estimate. The other shop just pulled the code and recommended a rebuild. He couldnt say what part failed until he pulled it apart. Replace torque converter, valve body, and install a Transgo shift kit for $1500-2200. I want to sell this truck but if i cant find someone to buy it as is then i want to fix it myself cheaply. I was hoping somebody who has worked on a 4L80E with a Trans slip could share their experience. What parts you replaced etc. I pulled the pan and found no debris and the fluid wasnt burnt. The 2500 has a trans temp gauge in the cluster so i know its never gotten hot. Truck has 121k miles on it now. The service engine light and hard shifts occured around 60-70k. Right after I replaced the flywheel which broke. Let me know if you have any advice. thanks. Brian
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snipped-for-privacy@hotmail.com wrote:

bob
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