I'd echo the earlier post... tail-lights seem to be unavailable, in any usual way. Someone may, of course, come up with some OEM ones when parting out a U-Haul
, but it gets more unlikely all the time. And the adapter kits, which added a square corner to the round surface where the stock lights
mounted, are mostly gone as well. [apparently
] Another option is to just fiberglass in the stock opening, and surface-mount a more industrial-truck-style tail-light on the surface of the U-Haul, probably a little farther around the corner to the rear.
If you haven't checked the U-Haul Facebook page, you might want to. They have a lengthy conversation going over there on making a new, original-style lens for the U-Hauls, and one member in particular is putting a lot of effort into getting that sorted out. They've also contacted one or two businesses about making new lenses. [Doing the initial set-up to start re-producing them is apparently the expensive hold-up there
And once you come up with a lens, there's still the issue of the deteriorated rubber flange/gasket affair behind it... also unavailable, I think. And apparently a leak-prone area. But there have been different work-arounds suggested for that
on the Facebook page as well. https://www.facebook.com/groups/UHaulCamper/
So some of this comes down to how valuable it is to you for the camper to be stock. The importance of "stock" varies a lot, from one person to the next.
Down-sides to my GM approach [which was spun off a comment of Mr Griebe's on the Facebook site
 Challenges of repairing fiberglass, in general, with all the "itchies".
 Can't readily go back to stock, once you've modified the corners.
 About have to paint
afterwards--at least the immediate repair area.
 Going to alter how the striping package works around the tail-lamp.
 Readily available parts, either from salvage yards, or new aftermarket ones from eBay or elsewhere. There was something like a 10yr span of Chevy & GMC trucks [and Blazers?
] that used these lamps, so not too hard to find used or aftermarket.
 And the new, aftermarket parts are cheap enough that I intend to get a whole new set soon, and toss my used set in a box for emergency spares. The 4 big pieces--bases and lenses--are $15-20 each, plus S/H.
 Should be "slightly" less vulnerable to damage, being inset a bit.
 Should be quite a bit less leak-prone, IMHO.
Well!... that's a bit more than 2 cents worth... hope it helps some.
p.s. My lenses were both cracked/broken, but I think all the pieces were still there. [LH side was more broken than RH
] And I saved the pieces. The rubber flange behind the lenses was pretty bad, but the lamp sockets are in pretty good shape. I'd probably part with all that, if you wanted pieces to cut-and-paste.