Transmission leaking

[Chamberpains]

I may be wrong but I don't see any reason that can't be pulled apart on the truck with the trans and auxiliary section in place. Drop the drive line to get up in there. And it should just unbolt and then seal with RTV silcone on the plate or replace the oring gasket if thats what that has behind it. There may be a "doughnut" rubber piston behind there that can be unbolted and replaced. Some times air and oil sneak by and get pushed out when they get worn or frozen.

Also make sure that isn't oil getting slung off the transmission output shaft seal. It may be a good idea to just throw a new seal in the tail shaft while you're up there any way.