Overfilled HD2500 6.0 Liter Tranny

[Scyry]

My Dad's tranny was overfilled by the idiots at the local garage he goes to. Anyways, he got the truck serviced, just the regular oil change, check fluids and grease everything routine. When they checked the tranny, apparently the guy figured it should be filled to the top. My Dad drove the truck the next day with his goose neck trailer to pick up ~160 bails of hay. It was a 2 hour drive each way. When he got home he noticed the tranny "leaked" a puddle of fluid in the driveway and he thought the differiental was leaking too. End up the whole underside of the truck was coated in ATF.

 

He took it into the local GMC dealer thinking a seal was bad on the tranny and the differiental when it was found to be over full. They still had to drain a couple quarts out of the tranny. Question is, could there be damage to the tranny? He towed for a good two hours, mainly on flat highway at ~65mph. That is tough on a transmission, let alone with it being over full. Just wondering if there is anything specific he could have checked out on it? Or anything he should watch for? Could it damage the seals, pushed some fluid into the transfer case, or damage anything?

 

Opps Edit:

Forgot the specifics, it is a 2003 GMC HD2500 4x4, 6.0 Liter with the auto and push button four wheel drive.

[GM-Tech]

It's likely there's no damage. The trans is vented (that's where the fluid blew out all over everything) so there's no pressure build up to force anything past any seals.

 

As I see it, you have two choices. Drive it and see if anything develops or tear it completely down and see if aeration of the fluid might have resulted in some toasted clutches... which I doubt. Seems like a big waste of time to me and I wouldn't bother if it was my truck.