Ok, so I found a couple of parts cars lately, and I am mildly interested in getting them. However they are not local, one is about 60 miles away and the other is about 100 miles away. When I went to U-Hauls website, it asks for the info about the tow vehicle. Anything less than 3/4 ton it will tell you your tow vehicle is too small.

The vehicles at my disposal to tow with are, 83 Blazer 2.8 Manual trans 4x4, 99 Blazer 4.3 automatic and MAYBE (depends on whether they want thier truck used as a tow LOL) 97 Chevy 1/2 ton with a 4.3. Donor cars are both H-bodies and would be towed with rear wheels on the ground.

Is Uhaul just wanting me to rent one of thier trucks along with the dolly?

No its a weight thing, they want you to weigh double that which you are towing.
Gets away from needing trailer brakes.
Pulling 3500lbs with 3500lbs makes for some long stops.

Thanks, I can see where that would be a BIG problem. Havent had "push and pray" brakes for years and don't need to start now.

i would use the 1/2 ton or the 99 blazer, and then if you dont want to rent a truck, just lie about the car you are towing, says its a metro or something, not the best but it will work.

No, don't lie and end up with the wrong tool. Just go directly to your local UHaul (not a sub-franchise if you can help it) and talk to someone there. I used the online stuff when I was moving, and it was completely different from what I got at the UHaul "store"