Just the fuel cell, because the original tank was leaking at the seam. Which brings me to another point. I only tied in the pressure and return lines. On my 2001, there is the vapor eliminator, which is totaly unhooked now. I don't know if that will effect emmissions at all, but mine still only gets the o2 sensor code. If you don't hook up the tank pressure switch, you will get a code for that.

2001 Sportage, 4" RSG lift, Cragers W/31 10.5 Micky Claws, Warn Manual Hubs, 16 gallon Pro Street Fuel Cell, Custom Snorkel, K&N Filter.
1989 Dodge W250.