Yes I am old now but I have had a cap on every truck I owned since 1972. The problem is the old cap never fits the new truck. :(
I like the cap level with the cab but my wife thinks it looks like a hearse.:E So my latest cap of course is 4 inches higher than the cab.
The dealer said the cap weighs 250 lbs. so with two adults and a large dog we have used up 750 lbs. of the 1440 lbs. cargo capacity of the truck before we start loading camping stuff.