New rear brakes are very tight

Are you sure that you have the proper shoes or drums. This happened to a friend of mine and when he drove the heat from the dragging wrecked all of his new stuff. It ended up being the wrong pads it also caused the wheels to lock up. So maybe you should take a second look just to be sure and knock the shoes from side to side to see if they are not sittng properly.
Better safe than sorry!!!

Yeah the new shoes look like the old ones, and the new drums are the same dimensions as the old one too. I am wondering about the parking brake, though. The cable is not too taunt, but the pedal cannot be moved even one click. It used to be able to be pushed to the floor.

Are your emergency brakes free........are the cables free?

They may be partially on if the cables are seizing up.

I'm going to try to figure out how to adjust the parking brake after dinner. The pedal is very stiff and doesn't want to move, but the cable looks okay.

Okay, the pedal and cable are now very loose and the drums are still dragging. It seems to be dragging less than it did when I first got them on, which makes sense. I've put 5-7 miles on them. Do you think it'll be okay on my trip tomorrow?

If it's not, you will smell it soon enough.

This just keeps getting better: a front hard line blew up last night. I'm not taking this truck anywhere now.

If one blew, you'd better check them all. I just replaced all mine this year.... saw one a little too corroded, and sure nough several were.

You might want to consider replacing with the Aeroquip braided stuff instead of hard lines. Costs more, but very durable and a lot easier to install.

Yeah I'm going to look at all of them and see what my options are. At least it blew at the end of my street and not somewhere in traffic. With the parking brake so loose there would have been no good way to stop it.

On the Dakota especially, look at the top pivot where the shoes come together.

If they come together unevenly, you may need to replace the backing plate. They should be parallel on the pivot. If one shoe is farther out or in than the other, the rear has been overloaded, and the plate is bent. If it is bent enough, you can adjust the shoes to match the drum while it is off, but when you try to install it, you will need to adjust them downn quite a bit. You can force the drum on by pushing it towards the front of the vehicle to line up with the wheel studs. The parking brake will not work, the pedal will be low.

Dont know if this is your pronblem, but I have seen it on a Dakota, and to a lesser extent, GM vans and some others.