[bwood]

I believe the 4L80E is longer and will require the crossmember to be moved back and a custom driveshaft. Also the ECM will need to be reprogrammed for the 4L80E as the internal gear ratios are different and it wouldn't shift correctly. What has killed you other transmissions? I wouldn't think a 6k# camper would do it. I know a few guys pulling more and have had no issues. What is your gear ratio? If it is kinda low (numerically low), like 3.42 or 3.23, you may concider a gear swap to something like 3.73. This will negatively affect your mileage when you are not pulling, but will take some strain off the trans. Are you using your tow haul buton at the end of the shifter? How fast do you drive while pulling?

BTW, welcome to the board.