Yeah, they are really nice. I got mine from Summit Racing. The only down fall is that most rack systems are for the standard Jerry Cans. I'm hoping that Dr Smash (Eric) and I can come up with a nice system for my Jeep.
I haven't started building my rear bumper and I was thinking of going this direction also. Any bad experiences with them? I mean leaking, hard to pour into the tank, stuff like that. Can you lay them on their side?