I just gotta new truck, (see sig.) and it seems like whenever I shift into, or out of 2nd. gear, something in the rear-end makes a "klunk" sound. It almost makes the same sound that it does when you shift into, or out of 4X4. Kinda like a "pop." Any idea what it could be? Right now I have 700 miles on it.

------------------
- 2001 F-150 XLT 4X4 Off-Road, S/C, FS, Black
- 4.6L Triton V8 (20 H.P. Increase)
- 5 Speed / 3:55 Reg. Axle
- Keyless
- Premium Audio CD
- Mods.
- K&N Cold Air mod.
- Flowmaster 40 (Stock Setup with 3 1/2" Gibson Tip)
- Bugshield
- Bedliner
- Ventshades