Missing plug under flywheel on 1971 Deuce &1/2

[Lemenhead]

I could use some help and advice.
I have a 1971 M35 that won't start. Looked under truck and saw I was missing a 1" plug. When I look into hole I can see the teeth of the flywheel.
Hoping motor isn't seized.
When I tried to start I got nothing not even the buzzer when I turn on the accessories. Charged batteries and the buzzer came on but nothing when I hit start except the buzzer sound dimming. Batteries tested low voltage of 9. I tried to start a few times until the buzzer stopped working while I hit started button. Now no buzzer. Im going to try some new batteries since these seam week. Hoping its just a battery problem
Questions:
Where the plug is missing and I can see the flywheel, should it have oil in it?
Where can I get a plug?
Anyone know of a mechanic in Indianapolis?
Thank for your time.

 

[Evil Dr. Porkchop]

The plug is just used when fording the truck so you’re all set. On most trucks there’s a holder with it right next to the hole.
Your problem is unrelated and could very well be weak batteries.