Thanks for all the info and support.
Got it done without incident. Had my son follow me to help with lane changes, stayed off the highways, and took 2-1/2 hrs for what normally takes 1-1/4 on the interstate.
My truck was about at its limit, but did fine. It's rated to tow only 6200 lbs because it has a 3.08 axle. If it was 3.42, it would be something like 9000 lbs., so I figure the stress was on my transmission. I have an extra cooler on it and it never went over 140 degrees but thankfully, the roads were pretty flat. The trailer obviously put a lot of tongue weight on the truck...I probably don't want to know! Not enough clearance, but never bottomed out. Should have used a higher ball mount but I went with what I had.
Yes, the U-Haul trailer is built pretty stout and the brakes worked well. It was old, but tires were new and the last brake inspection was in the spring.
I was not happy with U-Haul, though, as I had gone into the local store, reserved the trailer, and was told no issue because they have several on the lot. So Monday, I check in online and am told I have to drive 30 minutes to pick it up. The local guy confirmed he had 3 trailers but could not over-ride their central traffic coordinator and figured it was because I was towing one-way. I will admit to being harsh with more than one employee. It makes no sense. My 5-minute pick-up was almost 2 hours by the time I got the trailer back to the house.
Car is now in its new home and all is well.
Was kind of fun to have a Pontiac in my rear-view mirror.
Mike