Swapping transmissions....what else should I do when I pull the trans?

[project_x]

My 4L60e has been slipping and needs to be swapped.
Obviously I need to pull the drive shafts, remove the transfer case, remove cats...
So in addition to swapping the trans, I am looking at doing the following
1. Change U-Joints
2. Install Pump Rub kit and new fluid in NP246
3. New Transmission Cooler lines
4. ???

What other maintenance, upgrade/update should I do while I have it this far apart?

 

[strutaeng]

Engine rear main seal!!!

Is the transmission you are swapping a rebuilt unit? If it's a known good, used unit, replace the torque converter lock up O-ring on the input shaft. Maybe also the transmission front seal as well(?)

 

[89Suburban]

Trans mount

 

[project_x]

Engine rear main seal!!!

Is the transmission you are swapping a rebuilt unit? If it's a known good, used unit, replace the torque converter lock up O-ring on the input shaft. Maybe also the transmission front seal as well(?)

It is a known good used (rebuilt 20,000 miles ago).

 

[nonickatall]

Oil Pump O-ring, pressure relief valve and oil barbell.

 

[mattbta]

Engine rear main seal!!!

And rear cover gasket.