1964 Dynamic 88 2 door with 394/auto.
This is in the box with LF brake hardware. I thought it had something to do with the Speedo cable but I cannot remember (CRS) or figure out where it goes. Everything is back together and this is the outstanding piece. It has been probably six months since tear down. Any ideas out there?
Thank you,
Stephen

 

That looks like the bolt that holds down the brake line splitter on the rear. It is hollow in order to vent the rear differential assembly

 

Wow! I think you are absolutely correct! Thank you very much. It does not look like what came off as it was completely crusted with dirt and a big gob of undercoating over the whole thing. It was in the LF box, should have been in the LR so I was focused only on the front and thinking speedo cable guide. I got a poppet valve that fit the splitter block off of a mopar site so I was not looking for the original.
Thank you again,
This site is awesome.

 

If that’s the only part you have left over after a complete rebuild you are doing good!