David.. I had the heat expansion issue myself back in the 80's with ny-rods.
You could watch the surfaces move as the plane adjusted to the weather.
The ones I bought last year don't shrink and grow with the weather like they used to.

I make my own custom length rods..
I get the 12" push rods with one end threaded..
I use the pre threaded end for the clevis

I cut to the length I need and tap the other end with a 2-56 die..
The rod diameter is to small to use the tapped end for a clevis but with a little gorilla glue it'll hold solid in the ny-rod.