I actually stumbled across an article last night about clearance (marker) lights, and it's a legit federal mandate. Number, spacing, colors, location, etc. That's why you also see them on the tailgates of our K30's and such (if they're still original) It's every vehicle that's over 80 inches wide at some point across the body or driveline. Which they brought up the ford raptor (PUKE) and how it has amber clearance/marker lights on the front and red ones on the back of them because they're wider than 80" and a standard F150 does not have the lights because it's narrower than 80" (79.9" to be exact Lol).. And here I thought that was just retarded Ford Raptor owners trying to look cool and justify their p.o.s.' vehicle choices and bring more attention on themselves! Me personally, I think they're a nice look on an old Chevy! Heck, I even like the way they look on the late 70's Fords.. But, I grew up around trucks that always seemed to have them, so I'm partially partial to them myself!