Well after almost 3 years, I FINALLY got around to doing this modification, I pulled my mount off the truck took it to work, and elongated the slots with a plasma cutter, so I could rotate the tire towards the outside of the truck away from the parking brake drum.
Tm america was correct, there is only about 1/2" of clearance between the spare, and the drum.......it worked, but made me nervous.
I had some scrap aluminum, that I cut to the same size as the back of the mount. they were about 1/4" thick so I made four
plates, and marked, and drilled the holes.
I found 4 Grade-8 bolts long enough to support everything in one of my spare nuts and bolts buckets. So except for my time/labor there was zero expense.
I put the mount back on the truck with 3 spacers, between the mount and the frame, to move the mount outwards from the truck about 3/4"
Once everthing was properly cinched down, it was time to hoist the 395, and see if I had gained some extra clearance
When I first installed the 395, like tm america, I let the air out of the tire to help get her in place. It did help.
But I noticed a gap between the tire and the rim that had gotten small pebbles/debri in it that would cause problems later on when I had to use it, and air it back up.
So I aired the spare back up enough to close the gap, probably under 5 LBS PSI. I still had the 1/2" clearance between the spare and the drum, so I called it good.....for now.......
.....So with the spacers now in place, I hoisted the tire up to the mount, WITHOUT airing it down, and got it in place, then pulled it out toward the outside of the truck, I then tightened up the two nuts to hold the tire in place on the mount.
My rear 395s are mounted dish side out, as I didn't bother to flip the hubs, and I like the look. I have over an inch and a half clearance at the mid-axle tire, and at least an inch from the drum.
I now have plenty of clearance everywhere, except the tire is up against the tool box, but I can live with that. And now I have more usable bed space.
Wish I'd have done this years ago! Thank you tm america for your pioneering efforts in this area, for I would have never thought you could fit a 46" tire in a 39" tires spot.
But you CAN!
The reason I didn't put all 4 spacers in, was that I didn't think my bolts would be long enough, but they are. Maybe at some point I'll add the 4th spacer, but it's a lot of work, and right now I see no need for it.