Here are a few pictures of my Silverado! There are many many small modifications inside and out to make my truck resemble a 2003+ facelift GMT800. This truck and every electronic in it is still like all 1999-2002 trucks though. Listed below is some of the things I've done off the top of my head. (Nearly everything was sourced through my local junkyard)
Interior:
2003+ Full console (with Bose sub)
2003+ Steering wheel (Steering column spline shaft change, with a single stage express van air bag)
2003+ Gauge needles (Easy to find in 2002-2009 Trailblazers)
2003+ Black interior buttons (dimmer switch, 4wd selector, fog lights/cargo lamp)
2003+ Double din dash bezel with Sony touch screen
2003+ Dash cubby
1998-2001 Oldsmobile Bravada climate control knobs
2004-2006 Escalade Platinum speaker grilles (painted to match interior)
2006-2007classic Upgraded Gentex rearview mirror
2007+ GMT900 Column shifter
Exterior
2003-2005 Camper Style power extending mirrors (fully functional power extending and retracting Via a momentary Waterproof Reverse Polarity Switch, working signals in the glass as well as full adjustability using door panel mirror controller)
2001-2002 HD hood (Factory paint that already matched the truck, got from the junkyard for only $25!)
2000-2006 Suburban/ Tahoe front chrome grille
2000-2006 Black textured Tahoe door trim (The rear door trim length matches the length of extended cab trim)
GM Genuine Black textured mud guards
2004-2007classic GMC Sierra black outlined taillights
2001-2007classic Z71 Off-road rear bedside stickers
GM Genuine Upgraded aluminum front skid plate, Steel transferase skid plate installed as well
GM Genuine Tailgate spoiler cap
2001+ Dually/Quadrasteer rear marker light (this one was from a Quadrasteer Denali!)