I had previously drilled the mounting holes in the firewall to ¼”. Each hole was still off from lining up with the mount, so I marked each area with the direction the hole needed to move. I used a high speed bit in the dremel to move the holes. Don’t know how successful this was, but I tried. Next I drilled the hole to 5/16”, 21/64”, 11/32” and letter T. The first drill was pretty “grabby” because the hole was slightly oblong from pushing it whatever direction it needed to move. I used a strap from the roll bar to the mount as my third hand and installed a long ¼” bolt in a couple of holes. I the used the mount to match drill using a 3/8” reamer. Repeated this for the other 3 holes. Now that I’ve finished, I should have used each size bit to drill all 4 holes before moving to the next size—think I had tunnel vision and focused on one hole at a time—would have made for a lot less bit changes! Tomorrow I’ll insert the 3/8” bolts and muscle the mount into position.