The design of the T3 rear mounting bracket that I received wouldn't allow anything longer than the AN3 bolts that came with it, and those were slightly shorter than they should be (not quite enough grip length). I think the design of that bracket might have been changed on later examples. I wanted to increase those to AN4s at the correct length, so this is what I decided to do - I drilled everything out to 1/4" for the AN4s, then reamed the holes in the bracket to 5/16". I then made some bushings the correct length for the bracket thickness. Now the larger, longer bolts can be inserted, followed by the bushings, to give a good fit between the bolts & the oversize holes.

T3 bracket 1.jpg