Sorry I couldn't respond in detail before, been buried in my Shelby project. I dug around this morning and found a couple of spare pushrod tubes. Here's a photo of my installation tool, plus the tubes, which have not yet been fitted to the tool:
The tubes are 0.060" wall 3/4" OD aluminum tubing. I cut them to a 3" length with a tubing cutter, then deburr the ends. Next I stick them in the vise and start to squeeze them, until the installation tool will slide in, as shown:
After the tool is all the way in I squeeze down the vise the rest of the way, then release it and take the tube off the tool. The end looks like this:
Next I bevel one end of the tube in the grinder to make for an easier fit into the intake:
Finally I polish up the tube in the deburring wheel. It is shown here on the installation tool, ready for installation:
All there is left is to pound it into place in the intake. I get the tube most of the way in, then run a circle of green Loctite around the top and the bottom, so that when it is pounded into the final position the Loctite has a chance to wick into the joint and seal. Finally, here is the size of the hole that I machine into my intake adapters to fit these tubes:
I hope that helps. If you want me to send you the two tubes that I have, and the installation tool, text me - Jay