I have read mentioned that the Merc TRS Velvet drive boxes may have an extra clutch disk in them to improve holding power. I am soon to rebuild a 72c box soon and it will have a fresh 540 NA motor ahead of it. I’m looking to improve durability if possible. No issues with doing machine work to make it all fit and I have previous experience rebuilding performance automatic transmissions. Anyone have any knowledge of the details?

TRS Merctrans has lore of adding an additional clutch disk, and so benefits from additional atf pump pressure.

Not sure for the BW 72C. Try searching for 72C performance mods...the 72C was used in many applications not just on the TRS.

Did you do your rebuild yet?