Transmission went out while towing...

[BDPJR]

I have an '04 with <70K miles and was pulling around 1200 lbs and notice my RPMs were going up but I wasn't going fwd anymore. Coasted through a green light and pulled over. No lights and no codes to be pulled, 1-D and R do not respond. Fluid is clean and odor free, but is leaking from pan or seal haven't ck'd exactly yet. Some internet searching points to the tranny pump. There wasn't any noise before-during this fail. As the common saying goes..."has anyone had this happen?" Is it worth upgrading to a 4L80E and doing all the mods that go with it?