Some early dodge boxes were different, but I know the following is true for most Saginaw Dodge boxes. You can tap the box or tap the top cap and buy a new end cap. I have done both and like the caps better. I got my end cap from http://jkwoffroad.com/offroadproducts.php and drilled and tapped my own top cap. There is also a good write up on RamChargerCentral for where to tap the box itself, in the FAQ section I think.
hey man i appreciate it, ill probably end up going caps, seems a little easier than tapping the box itself, id hate to screw that up and have to spend that much more for another box