[Jordan Baker]

Here is the group 1.519 from the Otter parts listing.

It’s 1/4” OD tubing to the gauge. I suspect the line in my Otter is original. I can’t prove it but all the rest is still very much original and unmucked with.

I also found the below picture from the internet. It was a page that identified differences between Chevy and GMC dashes. The gauge on the left was for Chevy and the gauge on the right is for GMC. The difference was the Chevy 216 vs GMC 270.