Conventional wisdom (if you can call it that) calls for putting the fat cap towards the heat source, so in a UDS put it down. No need for a drip or water pan.
KCBS CBJ #56828
Team [URL="http://www.bigskysmokers.com"]Big Sky BBQ[/URL]
[B]UDS, Weber OTG, Maverick ET-732, Mega-Fast [COLOR=DarkOrange]Orange[/COLOR] Thermapen
[/B][I]"If I were just a bit more humble, I'd be perfect"[/I]