What mods, if any, do I need to make to 2nd generation rear disk brakes to install them on my 67 12 bolt?

the only "mod" (i hate that word.. sounds ricey)you need to do is take off the old drum brakes and install the new disc brakes. oh, yeah, you mght need to get the outside diameter of the axle wheel flange turned down a tad to fit inside the rotor, but not 100% sure on that.

I recently completed the bolt-on portion of this swap.By 2nd gen.I'm assuming you mean the WS6 Trans Am stuff from late 70's early 80's.I used 79 T/A parts-they bolted right on to my 69 12 bolt.I did have a slight clearance issue with the rotors fitting onto the axles but a few minutes with a Dremel tool opened up the holes in the rotors enough for everything to go together.I bought e-brake cables for the T/A because the calipers have some funky attaching points for the cables.The cables are much longer than the original Camaro pcs,so some backyard engineering is in order.I can't report on that aspect of the swap yet as the rear is still sitting on the floor of my garage,it's about 12 degrees in there right now-c'mon springtime!I'm not sure yet what master cyl.I'll use-either the T/A piece,if it will bolt up to my existing power booster(original disc/drum car),or the 68 Corvette master,I'm told that will also bolt up.I figure I'll investigate the M/C issue more closely when I get back at it in the spring.Hope this helps,good luck.

The only thing I'll add to what has already been said is that I would recommend you clearance the AXLE flanges for clearance rather than the rotors. Then you only have to do it once and if you ever get stuck needing a new rear rotor without your dremel, you're in trouble!

Good luck,
Bill C.