Those are indeed double side Guide glass lens D68 Turnsignals. Brad the ones you have pictured are the single sided Guide D68's,like the ones on my '52 GMC COE. Both were available from GM Dealers, as optional accessories. I have a page in my GMC accessories catalog of both styles. I used to have 8-10 sets of those, some NOS, some I restored. Had no trouble selling them. Those tear drop looking lights that were on there, were cab clearance lights someone probably had there at one time. Never seen anyone put them there before. I've owned close to thirty GM COE's through the years, & the Guide Lamps were on most of them. If you click into the link below of my '50 GMC 1 ton, you'll see a set of the single sided D68's on it.
