I feel it's only fair to warn you..
http://www.67-72chevytrucks.com/vboa...postcount=6698
and btw, lmc refunded the mirrors and return shipping, not the first complaint on these the gal said..
no idea if the actual oems are any better but the aftermarkets don't work at all..
and I've heard that around the forum a few times..
oh, and agree with above, welding closed 100% with filler metal pieces for larger holes is the only way to go..
good luck!