Wow, thanks for the thoughtful response ruderunner and everyone else who has replied.
Frankly, the Mazda runs great, I could probably get at least another 50K out of it and it's been paid off for a long time. But, the value will only keep going down the longer I drive it. And, like I said previously, it gets tiring driving it in stop and go traffic for hours on end. It's time to move onto something new.
I've thought hard about keeping the D100 and fixing it up. I looked for a '70s SWB truck for a long time. I had to do a lot to it when I first got it. I had to put new axle bearings and seals in it so I sprung for new drums too and made new rear lines. I rewired the entire truck as well, everything works as it should. I lowered the rear 2". It actually handles OK for what it is. It's been fairly reliable after all the stuff I did to it.
That said, it mostly just sits and I feel bad about that. It needs to be driven regularly like any other vehicle. It's hard to justify spending a bunch more money on it to make it marginally better. I dunno, a new truck just seems like a better idea for the long haul.
If I can swing it, I'd probably sell the D and find a driver type Mopar to spell driving the truck every day. I could do the daddy taxi thing in the AM then hop into something cool to get to work. That's most likely what I will end up doing.
My wife drives a Subaru Outback that replaced our '01 Cherokee. They are really similar vehicles actually. Our kids are 8 and 4 so they are still little. The little one is kind of a pip squeak so he's still in a car seat. They would love a truck, we've talked about it a lot. They like daddy's green truck but they can't really ride in it.
Still unsure whether a Durango would be sufficient but it seems like 11secdart did it with an older one. I'm surprised you were towing an enclosed trailer with one of those? Guess it was OK? Wonder how they stack up against the newer ones? Can't image they were more powerful (unless it was modified) and the transmission was not as sophisticated. I have no doubt the newer ones can pull an open trailer, they advertise them like that.
