Just bought a 2006 3500 express cutaway, I believe they have the 4L80E tranmission from what I have read, correct me if im wrong. And I have 1 or 2 leaks. The first one I cannot find anything on, this is definately an active leak as it is spotting the driveway. But it appears to be from the plug pictured, two of the wires on the plug were also broken. Any ideas?

Also, there may be a leak at the rear seal, although it is not actively leaking and carfax does show transmission service recently so maybe the fixed it? There is a ton of sludge below the rear seal area.

 

It's called a wiring harness. It has an O-ring that can cause a leak and also sometimes the actual pins can leak so check carefully. To remove it you have to drop the pan.

 

Drop the pan to remove/replace the external harness?

Also, is there a DIY for replacing the rear seal/bushing, might be out of my league but I would like to make sure before I pay someone to do so.