Of course Seth, since you found it on the internet it's gospel right??
Close, my open top measures 52" by 43" - - that to lay a rubber mat in with about 1/8 to 3/8 clearance all the way around
Of course the wagon could have carpet in the back to make up the diff.
John
P.S. I'm expecting nothing less than Oscar caliber work from Moab.....Mr.