Wanting to buy a new or used set of pushrod guide plates for 289.
Best part number I can find is: c90z-6a564-b
Do they have to be the Ford part number? Those things are available by seemingly everyone.
The Ford parts are just stamped steel. You really want the black oxide aftermarket ones and by all means use the black pushrods with them.
The blackened pieces are hardened. If the parts aren't blackened then they aren't hardened.
The standard "silver" pushrods, even if they are designated as hardened, are only good with stock valve springs. They will bend under the load of dual or triple springs.
Yes, aftermarket ones are available pretty much everywhere and cheap. Just thought I'd try to keep it "Ford".
Realize that the "black" is the "black oxide finish", not an indicator of the heat treating process for compatibility with guide plates or other guiding surfaces; and that hardened pushrods that are compatible have been, and are produced as "unblackened" as were the original 289HP and BOSS 302/351's, etc..
A quick test is to lay a razor blade at approximately 30° to 45° to the pushrod surface and scrape, if the razor blade digs in, then they are not hardened for the guide plate application. ;)
Scott.