Yep! The GVWR is 10,000# even.
Interior length is 14.5' (even though some are advertised as 15' or 16').
Interior width is 92"
Rear door opening is 72" high
Deck height is 40" from ground.
Some have pass through doors but I've noticed alot of the 05 and newer one's do not.
I can't remember the exact empty weight before my additional equipt but it was under 7,000#. The Penske website shows 6800#
Gas mileage is about 11.5. However yesterday with the help of Lucas fuel treatment, Lucas oil treatment and a good tailwind I achieved 13.29 mpg. My best ever on this truck. We'll see how long it lasts. I was about a quart low on oil so I used a quart of Lucas oil stabilizer. It looked so thick as I was pouring it in (like honey) it almost made me nervous but something did the trick.
Also make sure if your friend wants to stay under 10,001# to stick with the GMC chassis.
Penske has some Ford chassis with the same box that have decals on the outside of the door that states "GVWR Under 10,000 lbs" however when you open the door and look at the mfg sticker it shows GVWR as 11,500.
I got stopped yesterday by Indiana State Police on 231/67 south of Spencer. The officer did not really care to see my license or registration but immediately opened my driver's door to check sticker for GVWR. He said "We are doing truck inspections today and you are under the limit. Have a nice day" Got back in his car and left.