94 Caravan - cooked transmission - cause?

Base info... 1994 Dodge Caravan, 3.0L V6, 41TE 4spd tranny running ATF+3. B&M Aux tranny cooler designed for towing up to 7k lbs.. 103k
miles on the van.
I pulled a 2200lb popup camper from Daytona Beach to Brooksville in Florida. Didn't really notice any problems. Went to go back out, and the tranny started to shift funny. Bouncing bewteen gears.It did this for a few miles, and then ended up losing all gears. Going to neutral for a few seconds, and then going to D would bring a few moments of movement until it lost it. Once it picked back up, the tranny would whine for a few seconds, and then go quiet.... drive would then resume for a few seconds, then go away..... repeat repeat all the way back to the campsite. (About 10 miles)
Scanner revealed a Loss of Prime error, 4th Gear ratio error, and Torque Converter Lockup error.
Fluid was clean smelling, but darkened. There was a lot of debris in the fluid (clutch material).
Had the van towed home. Dropped the pan, and the magnet was covered in clutch material. Changed fluid and filter, and drive is restored. CVI's are all within spec listed in the 94 FSM.
A couple of months before this, I noticed a chirping noise coming from the engine compartment. I just thought it was a bad belt tensioner, and was waiting until major tune up time to change it. Now, after this disaster, the noise is more pronounced. Its the tranny. Noise is only there when in R or OD/3/L.
When driving slow (under 10mph), the tranny feels like it is catching and releasing. Chalking this up to toasted clutches.
So the tranny is cooked. Question is, what caused this? Yes, I did tow in OD. Florida is 90% flat land. When going uphill, I pulled it down into 3. (Even in 3, according to the scanner, the TCC never stayed locked...)
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Honestly, I'm suprised it lasted as long as it did. That transmission wasn't designed to pull much more than gross vehicle weight.
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corning_d3
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He right ^^^^ Ive put alot of them in.
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J-Mech
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Sounds like it just slipped under load. Generates a lot of heat and burns off the clutches. In a few seconds, it's over.
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