This is a quick, down and dirty, way to install a Powertank using the basic powertank bracket without cutting, drilling or marring the interior.
The basic idea is to use the tie-down channels in the second gen. Use the pieces that goes into the channel, but not the tie-down top that screws into it. Instead, you use a 6mm hex-head bolts and flat washers. Put the washers on the bolts, and put the bolts through the bottom part of the powertank bracket and screw on the channel pieces. Put the channel pieces into the channel, and tighten the bolts. This effectively bolts the powertank bracket to the channels.
Because it is held by only two 6mm bolts at the base, the bracket needs a little additional support from the top to keep it from moving too much. Take a suitable strong steel cable and run it between two of the ceiling hooks, then bring one piece of cable down to the top of the bracket. Fasten to the bracket with a turnbuckle (with hook) -- available at Sears hardware -- and tighten enough to control any movement.
See pictures below for a visual presentation:
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