Help tracing drivetrain ATF leak

hondaman900

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I have a 2004 Expedition 4WD with the 5.4L V8 and 183k miles. There's a drip leak from the drivetrain that collects on the crossmember and drips to the ground. It doesn't seem to be the transmission pan. I degreased the undercarriage to try to find the leak and it seems to be coming from directly above the crossmember that holds the tranny mount. There's a section or drivetrain between the end of the transmission and the transfer case, looks like a separate section or entity, and as far as I can tell the leak is coming from between the end of the tranny and it. It's very hard to tell. Here are some pics, you can see the red sheen from the ATF. Any advice on how to pinpoint the leak and what's involved in repairing it is very welcome. I have to drive the Expy from CA to VA in a couple of weeks and am concerned the drip could develop into a major breakdown. Thoughts?
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hondaman900

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Thanks Frank, and I researched the bulkhead fitting so I now know what you're referring to. However my transmission looks different. But the leak does seem to be coming from the passenger side corner where you show, so maybe there's a different sort of bulkhead fitting on mine in that area that's not as visible as yours?

Here's the driver's side rad corner of the pan:
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And here's the passenger side rear corner, which seems to be the origin of the leak:

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I did check the ATF level on a hot transmission in park, engine idling on level ground and the fluid was at the top of the "do not add" section of the dip stick. I pumped about a pint out and got it to 3/4 up the hot range on the indicator.

I'm wondering if the overfilled condition was perhaps causing fluid to come out the vent, although there's meant to be a hose that should take that away, if it's connected? A pint wasn't that much of an overfill, so not sure if that was enough to vent out.

Thoughts?
 
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hondaman900

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Frank, it looks from what I can tell your transmission with that connector is a 6-speed, whereas mine seems to be a 4R75W 4-speed. I think the connector labeled "9-pin electrical connector" in the pic is my bulkhead connector. I'll check it for the leak source but it's a ways down from the apparent leak location. Perhaps the ATF flows that way though before dropping down?

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