The tie downs, the parts that bolt to the frame of the truck, are truck specific. I couldn't use the tie downs from my 2006 GMC on my 2014 Chevy. Check out the Torklift website for all of their products.
www.torklift.com I am sure there is something similar for Happijac, but I have had Torklift on both trucks since I bought the camper.
The turnbuckles ( Fastguns )that go from the tiedowns to the camper are universal, but there are different lengths. Long ones for frame mounted tiedowns and short ones for the Happijac system that mounts to the truck box.
I think you would be best to buy the tiedowns before you leave home, and then he should have the rest.
Good luck
OH and welcome to the forum. Lots of great people with lots of knowledge on here.