Ask around Hollywood and no one will tell you they want a flat bottom. But any respected Jeep owner would jump at the chance to have a bolt-on flat bottom skidplate. And of all the Jeeps that need additional underside protection, the '07-'09 Wrangler is near the top. Sure the factory JK skidders were designed to support the weight of the Jeep, but a constant barrage of rock-strewn trails will beat those factory skidplates and many of the unprotected vital components into submission. Enter Poly Performance, a company that has experience in building skidplates for Jeeps that hit the rocks all day at a snails pace and battle Baja at 90mph. And that's pretty much what the company built for the JK Wrangler in the form of a three skidplate package that protects the engine oil pan, tranny, exhaust, and transfer case.
The underside of an '07-'09 Wrangler isn't really protected all that well, especially if you have a manual transmission. The exhaust on our manual two-door was taking a beating. We were lucky and hadn't hit the low-hanging engine oil pan yet, but we had slightly bent the thin transmission crossmember. The Poly Performance three skidplate package replaces all of this with 3/16-inch Grade 50 A-572 steel plate. | 
First you need remove the triangular transfer case skidplate (and automatic transmission skidplate if equipped). Then several of the pre-existing threaded mounting holes in the framerails need to be drilled out to 29/64 inch and tapped with a 1/2-20 tap. |
Using a cutoff wheel, angle grinder, or reciprocating saw you need to cut off the forward-most 3 inches of the factory gas tank skid plate. Watch out for the fuel tank, it's made of plastic and it's close by. | 
The transmission should be supported with a jackstand or tranny jack while you remove the factory transmission crossmember. All of the original crossmember mounting hardware is reused so don't toss it. |
The Poly Performance tranny crossmember/skidplate is heavy and hard to maneuver and mount. It can be done by one person, but it's easier if you have a buddy hold it up while you install the included countersunk bolts. Use plenty of anti-seize on the threads because this area has a high potential for rust. | 
There are access slots in the Poly Performance skidplate that are way-helpful when tightening the mounting hardware. However, a magnet on the end of a stick is pretty much mandatory for getting the nuts started on the passenger side crossmember bolts. |
We needed a pair of locking pliers to clamp our factory gas tank skidplate in place while drilling the mounting holes and installing the self-tapping flush-mounted bolts. Be careful when drilling because the soft plastic fuel tank is just on the other side of where you are punching holes. | 
The oil pan skidplate mounting brackets attach to the factory motor mounts on both sides of the engine. The skidplate attaches to these and then to the new heavy-duty crossmember/skidplate. It's an intensive install, but the skidplates fit up well. Even the drain hole cut into the oil pan skidder worked perfect when we changed the oil. No mess, no fuss. |