[Marc S.]

We use 3/16" pop rivets. These are awesome because they go perfectly in a No.7 hole(clearance for a 10-32). The gussets seem OK in size just as long as your using a good belly pan. It might just be me but it looks like your using 1/8" wall end-rails, 1/16" is plenty strong there.

One thing that will keep your gearbox clean is getting rid of all unnecessary bolts. For instance the same bolt that holds the top of the motor in can also go through the top standoff. If your making these plates with a cnc or water-jet, you can round the corners and try doing some pocketing. If you go the cnc rout then making the plates identical will keep your (cnc)sponsers happy.