In the past, we used ballistic anchors with manufacturers approval. We hung a low bay fixture on each anchor. For what you are doing is I'm with the rest of the guys, dyna bolt unistrut to the concrete. The number and size of anchors will depend on the weight of the unit. The anchor tensil strength should be on the box
I hear you about the "Supply Houses" anymore. Times are tight and the supply houses become "order houses", because they may not have what you need right now, but they will be happy to order it for you. Problem here is that it might take a month to get the part, cause they only order once a month from a distributor. Unless you want to pay the "overnight" freight fees.
I have not personally been in a supply house in about 6 years. I tried my best to stay with the local guys, including the days when there were 'hardware' stores.
We all have seen the shrinkage of inventories, and the outright closings of a lot of 'small' local guys. 'Stock' is dwindling to conserve $$$
The best systems that I dealt with for obtaining hardware and 'odd' items were WWG and Mcmaster Carr. McMaster used to amaze me with same day delivery (order b4 11AM) and the shipping was not that expensive.
