I have the RDS 60 w/ toolbox. All the answers have been addressed to the OP, but I'll add one more comment....
After using this box since 2006 (on my 6.0 F250, then transferred it to my 2012 F350), I added an inline fuel filter last year. That was a mistake! Since it is a gravity feed system, the inline filter added enough resistance that the tank would stop draining to the stock tank when it dropped to about half full. I finally got around to pulling the filter off and have it straight feeding again. I change my fuel filters on my truck as required so I don't see the need for a filter between the tanks and should have never added it.