Another option for internal threads is using threaded standoffs instead of spacers for gearboxes and other parallel plate applications. We started doing this on 2168 in 2011 and it has been a positive experience. No more looking for spacers during repairs.
Here is an example part from
McMaster.
Also for our bumper mounts we used some Riv Nuts (also from
McMaster) installed in the frame, and some large thumb screws as fasteners.