My truck version has a cummins diesel in it. The guy I bought it from took all the parts from a low mileage wrecked first gen dodge and put them in the dreamer. (complete drivetrain and rearend, and added a gear vendors overdrive) Still needs work to it and likely be a couple years before I get to it but this is the first one I've seen in person so thinking they are pretty rare. From some sites I found, they say anywhere from 300-500 made but not sure how accurate that is.
My hauler version (with the bed) I bought from a guy who had it in the early 90's, sold it, and then bought it back a few years ago. He bought it from the original owner I believe and was pretty sure it was done in Texas. It has a 440 in it and is more stock than my other one and from what he told me, very few made. There is a tag they found behind the interior panels that has a number "10" on it and he thought that might mean #10 made. Not really sure but would sure love to track someone down who might have been involved in the production of these. The flat deck is around 20 feet or so with pull out ramps built in so very easy to pull vehicles on it. I've only driven it a few hundred miles and plan to paint it eventually and fix a few things here and there and then use it to haul around some of my other dodges.
If any info from me would help you in any way with your project, just let me know. The vehicles are parked at my buddies place for now and will likely stay there until I get time to work on them.