What is this plug for?

Can anyone tell me what this plug is, and what it's for? There is one on each side of the transmission housing.They are small plugs and when I unscrew them, a tiny little bit of dark colored oil comes out, and there is a spring behind it.

Follow Ups:

• Re: What is this plug for? - Travis 19:27:10 07/06/25 (3)
  • Re: What is this plug for? - Bruce Dorsi 11:01:00 07/07/25 (1)
    • Re: What is this plug for? - Travis 11:41:34 07/07/25 (0)
  • Re: What is this plug for? - DED 06:07:33 07/07/25 (0)
• I have them on my late '52 8N - Ed Gooding (VA) 08:27:00 07/06/25 (4)
  • Re: I have them on my late '52 8N - Walt/Tx 16:17:58 07/06/25 (3)
    • Photo of Walt's Jube with mystery plugs - Ed Gooding (VA) 21:16:28 07/06/25 (2)
      • Re: Photo of Walt's Jube with mystery plugs - jmor 17:38:55 07/07/25 (1)
        • Re: Photo of Walt's Jube with mystery plugs (url) - jmor 17:44:10 07/07/25 (0)
• Re: What is this plug for? - Dead Eye Dave 07:13:27 07/06/25 (1)
  • Re: What is this plug for? - Travis 14:21:13 07/06/25 (0)

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