I was thinking about doing something like this to my 85k10. I was thinking of getting some lights from the salvage yard, then use mask off the back side with some foil tape. Then cut off the old bulb and terminals. This would leave a hole. Then clean off the surface. I would then check and see if if the new replacement slide and lock Bulb fits. Once I got the slots. Cut right I would then fiber glass the back side. Once it's hardened I would cut out the hole one more time. The fiberglass would insure some redgidity. After doing all this I would install the new lights on my truck and adjust them. I haven't ever been a fan of how bright my low beams are on my dual headlight 85.