I used the downpipe right off of the motor, it fits around the front axle / diff nicely and crosses right where the stock Eagle/Jeep would. Since i used the transmission mount from the XJ it even slides in the stock notch for it. After that I made a 45* bend towards the exhaust, about 10" or so straight, then another 45* to go back to the muffler (I put on a Thrush muffler, dear lord it sounds mean).
The battery tray, just unbolt from the passenger side, carry to the driver's side, figure where to drill and mount it. Both sides are identical minus the holes for the tray.
XJ gears won't fit the Eagle diff? Sure looks like they do, considering I've already taken the gears from an XJ and put them in a differential but the pinion is screwed. I think there were 2 different pumpkins for the front of the Eagle, XJ gears fit in some but not others.
Unless you're talking about something else. I am rather tired and about to just glue the
gauges to the f*ing dash and call it a day.