There are ~60 spot welds, 30 per side. There are two welds all along the outsides of the members, where they attach.
My concerns in the above post are about the (relatively) large box member faces, but now ... (keep reading)
In this case, I think my best bet is to:
1) clean up all of the remaining metal from my drilling; remove burrs, dolly flat, etc.
2) clean and prime (coat; cover) all of the surfaces, let dry; repeat until satisfied
3) carefully position and clamp all members in place (or at critical points, if low on clamps)
4) clean all drill holes once more w/ bit / w/e
4) weld all spots (this is done by using a welding spoon on the back of the hole, and filling the gap that remains)
5) clean exposed welds and prime all weld points
The theory above (in this post) is the same as from the factory: all of the surfaces are protected, and once they're welded they won't move and e.g. rub the coatings off. So, do the same for repair. The trick is that I'm welding holes
rather than spot welding flanges. I can ensure a proper ground for welding at convenient/exposed faces and re-finish if needed. Welding spoon is to help contain the weld and shielding gasses; the spoon can be e.g. copper or aluminum (something w/ higher melting pt.); I plan to use a folded aluminum sheet (license plate) clamped behind the spots.
Given the above, the only thing I'm really
concerned with now is getting to the backsides of the welds that are within the box members. There are ~8 per box; box is ~ 1.5 x 6 inches.
Also, Butler Auto Group / Lexus South Atlanta is a pain to deal w/ when there's issues: they listed the part for $100 less than others, but claimed they received four
damaged units in a row, but apparently this doesn't register as an issue worth contacting the customer about. Needless to say, I canceled my order and ponied up to a local dealer who had the part in two days. Anyway, the part they sold me was damaged; finish scratched and surface rust showing, as well as being bent in a few places. Maybe BAG / LSAP wasn't wrong after all, but I have zero time for being vehicle-less. I don't know if it's even worth taking up the issue at this point.
Additionally, don't keep any hopes for the parts you're taking off -- unless you get the spot welds exactly
perfectly drilled out / removed (note, they're variable size, and a handful are in awkward locations), you're not going to get anywhere close to saving it.
Oh, and last, if you attempt to do this, make sure you evacuate your refrigerant before you setup the vehicle for the work. Either that or you'll be calling e.g. a mobile HVAC tech to do the evac. for you. If you're "lucky", you'll have lost the refrigerant in the accident and won't have to worry about it.