henry,
if you have the 99.5-later truck, the "DIY" airfilter set up is REALLY EASY, and no more flat filter.... cost about $40 for the (WIX 46637) filter, hose clamp and 3" long pc of 4" exhaust pipe, takes about 15 minutes to do... the early 99's might be a little more diffucult, the pipes are shaped a little diffrently, looks like it would take a 45 elbow when I looked at my friend's early 99.
If you have the later truck, do it once with the DIY air filter mod... there's write-ups on here, do a search.... Good luck