YES they are fragile! I've been through that new hell just this evening. I am disappointed in my "good" housings. They're only a couple years old; I put them on when I did my engine swap. When I went to take them off to do this retrofit, the tabs were cracked and broken already. TERRIBLE design. I've got a fix for that, though...
I actually took an extra set of brackets that I had in my garage, brought them inside and I carefully (not carefully) cut the old tabs off completely and remade some using crimp-on electrical eyelets and JB Weld. The new tabs are definitely stronger than the originals. They're bulky and irregular shaped, but they are aligned properly for the mounting bracket. This is a problem that I recall having when I put these lights on the car a couple years ago. The holes in the tabs didn't line up well with the channels in the brackets. They probably were stressed/cracked from then, but they hadn't completely disintegrated until I removed the housings a couple days ago.
I've got some notes on my progress:
1. As though I didn't know this already, silicone sealant is really damned messy. I'm going to have a lot of cleanup to do once I get my "second prototype" ready to install.
2. Even with a good template, adjustment at the time of fitment is still necessary. Whatever guide I come up with will be more of a rough walkthru, and less of a cookie-cutter "you can follow this exactly and get a perfect result" kind of a thing.
3. The aftermarket housings (Eagle Eyes) that I'm using must have a more rounded slope where the top edge of the lens rolls off and goes down the face. Using my old yellowish hazy lenses, I had no interference between the shroud and lens. With the "new" lenses, further modification of the shroud and even the lens itself a bit was necessary. I think when I do my "final" install, with brand new housings/lenses I will pain the interior edge black all the way around to help conceal the raw edge of the shroud that I end up with. The edge is behind the section that has longitudinal flutes molded into it so I had glued some aluminum foil over the cut upper edge of the shroud and through the fluted lens you couldn't really tell it wasn't chrome. With needing to grind out a bit of a pocket in the interior of the lens for the shroud to fit, I think the best course to conceal the work done will end up being a nicely masked black strip all the way around. The Eagle Eyes housings that I have deviate already from the OEM in that the floors are already flat black instead of dull silver, so this should match up well with the unit when put in place. They also used grey sealant on these housings which I attempted to remove entirely but still missed some of the more aggressively stuck patches, these contrast with the black RTV that I am sealing the housings with so in the final, greater care will be taken to prep this joint. I'm being "quick and dirty" with prototype 2, so I don't really care that much. Nothing I end up doing is going to necessarily be show-car quality, but I'd like people to follow along and maybe get much closer than I do to that level of perfection.