Recently upgraded my Reflecto-lite 1400 tails. I was cutting people off all the way across America without a left blinker. After much research and disappointment I can't just buy a new set, I rebuilt the existing. Overall I am very pleased, expensive, but worth it. My approach is a bit different from others I've seen, so I figured I would pay my forum dues.
A lot of people use plastic for a frame, but this seems cheap to me; I went with Aluminum. Also, I wanted to maintain the factory look as the rarity of the part speaks to its importance.
Disconnecting from the truck, I added male/female spade connectors to each lead for future repairs, added 4 new L-base bulb sockets (2 each side), wired the reverse to trigger both filaments, red LED bulbs for brake, white LED for back-up and Standard bulb for blinker(the idea of using resistors is concerning to me)
Cleaning everything up I painted the taillight fronts, super-glued a few bad cracks, applied butyl tape and applied my vanity cover. An Aluminum rectangle ($110) was then prepped, primed and painted to match. This 1/8thick aluminum is plenty strong to pull my cracked and warped frames tight to the truck. New stainless screws painted to match (only 6 per light) and I'm down the road.
If I was to do it over, I would of used thicker butyl tape, (1/4") and next size up stainless screws (#10?) as some of the holes were stripped.
I've included a pdf of my vanity cover template. This was emailed directly to Metal Supermarkets(national chain) and I stopped by a few days later to pick up. Fit PERFECTLY.
Tailight.pdf