Re: 3/4" o.d. tubing
I'm figuring that the top of the tube is splayed a bit, and that the I.D. down lower is .755-.760 which would be normal by U.S. standards.
What size is needed for the reciever end at the seat? Is it also 3/4"?
The newer ones are swaged to a smaller diameter at the end that the seat connects to.
Lenny is right .065" wall Chromoly is not going to bend! If you are not sure what type of tubing you are getting, and you want a safety margin, use .090" wall. 1/8" wall Aluminum will be fine also.
There is no need to use solid rod, but if that's all you can find it will certainly work!