Ford F-150 - 1997-2003 :: 2001 - Low Moan At 70 MPH Come And Go - Overdrive On / Off Indicator Flashing

I'll start with truck specifics. 2001 Ford Expedition, 5.4, automatic, 141,000. We just got the truck 4 months ago, second owners. Seemed reasonably maintained, other than Ball joints.

This afternoon, my wife and I were cruising along on this warm 90 degree summer day, out running some errands and having a good time ( we both had today off) about 70 miles from home. When we pulled into one of our spots, I noticed a few drips heading in the direction of under the truck. i simply thought the AC, which had been running full blast for an hour, was dripping, not a huge deal. didnt think twice, a few drops, no biggie. We ran a few other errands, then got back on the highway going 70 MPH. I heard a low moan at 70 that would come anbd go, I thought I may have had a tire howling on the road or possibly the start of the shifted belt. Noise was intermittent, but went away after a few minutes of driving. another mile or two down the road, I noticed the rear window seemed oily. Suddenly, things began to click, oil blow on the back window, funny noises, drips, something was leaking.

My eyes darted to the gauges, everything was holding up as i made it to the nearest exit another few miles away. As I hit the exit, i noticed the overdrive on off indicator flashing at me on the shifter stalk. I roll to the stoplight at the end of the ramp, suddenly, the tranny slips. There was no slipping on the highway. the truck did get a grip and get me from the light a few hundred feet ( there was a line of traffic behind me) to a parking lot where I could stop and inspect. as i shut it off and peeked under, fluid was pouring out of the bellhousing of the transmission. i called pops, he brought down the truck and trailer and we winched it on, dragged it home.

So, now the truck in in my garage, on the lift (yes, im spoiled) and I'm surveying the damage. oil leaks seem to be directed only from the bellhousing area, other places only have blow by residue on them. Fluid is a little dark, but not burnt smelling, and within tolerance. I see darker fluid at work when I do transmission flushes all the time.

So, now the questions. First off, I would be guessing that the front pump seal decided to go out, does that sound correct to you gentlemen? I'm going to start digging in on removing the transmission tomorrow, and hopefully get it out by the weekend. Also, from the fluid condition, do you think I got lucky, or do you think I did damage to the transmission?

As for knowledge and resources, I'm a mechanic, I do mostly brake, suspension, exhaust, and maintenance work (oil changes, tranny flushes, other stuff like that) so I do have a decent knowledge base, and while I have swapped transmissions before, I dont have a huge knowledge of tier inner workings. I do have access to a scan tool, and other diagnostic instruments, but as i stated before, not a full working knowledge.