I got some info for you, my tank is a modified RDS #71804. I bought this thru DFA (Vegistroke).It was a 37 gallon,that is now 36 with all the plumbing in it.They also offer a Excursion tank for under body applications(30 or 40 gallon). Either go on the furom over there or call and talk to jason or james directly @ 1-866-369-5172. On a side note,with my tank I did have to downsize my spare,and drill a hole thru cabin under jack storage.On the underbody tank there is also some tricky install parameters.There prices are a little high ,but there quality is higher.I too own a 2000 X limited with the 7.3(green and tan) and wouldn't put any lesser quality unit in it...........
