[bobkatfly]

I really appreciate the input from everyone.

As far as the insert length, I'll determine that when I finally get out to work on it (have to do truck brakes first).
The drain plug is 3/8-16 and although 1/2" long inserts come with the kit, they have inserts as short as 5/16" for that thread and the length from under the plug head to end of threads is 5/16". A little longer on the insert should be okay.

There is a dipstick port on the top so I could pressurize it while drilling/tapping as well as testing. I will definitely pressure test after install but I think using grease on the drill bit and tap will be okay. I can also get a Q-tip in there with grease to pickup chips.

As far as re-tapping without using an insert, I did that initially but I don't like the way the plug feels threading in so pretty sure the insert is needed as well as a new plug. I'll re-evaluate when I start.

Maxum, I'll try to remember pics also.