[smc4C]

The other end looks like it's connected to the bracket. So, I'm thinking after market something was added, then removed but they missed that. If it is connected to the bracket then it was used as a ground source. You should be able to remove it and toss!

BTW, your trans oil reservoir cap looks pretty beat!

 

[smc4C]

Any chance it’s part of the battery tender plug?

OOoooo... great guess! It is a ground, but I'd still prefer to connect to the Neg. on the battery.