OK, I had the right sizes above, 10mm square drive for the fill plug, 13mm square drive for the drain plug. Both are male square sockets.
I was able to find the 13mm one at the local NAPA Auto Parts, but they had to special order it in. Part # S38SQDP13M, 'Oil Drain Plug Socket, Square'. They did NOT have a 10mm version Male, they only had listed a Female square socket. After some looking, I was able to find the 10mm Male at the local PEP Boys in stock, Part # 2037, described as 'CTA 10mm Square Drain Plug Socket'.
PEP Boys had theirs for $5.99, NAPA had theirs for $7.99.
NAPA, Part # S38SQDP13M
PEP Boys, Part # 2037
If you are doing this work yourself, PLEASE DO NOT use your 3/8 and 1/2 inch socket wrench for these plugs! You WILL round out the holes because the sizes are not an exact match, the holes are both slightly larger than these wrenches. It might work once, maybe twice, but eventually you'll just spin the thing and be screwed.
This reminds me, next time I'm at the local salvage yard I need to score an extra set of these plugs as a backup, now that I have the right tools to remove them.