Interesting topic. I just picked up a good used set of 273 rockers. I'm assuming they all had banana-groove shafts. The set I got was in good shape, but the interference fit on several of them were pretty much wore out. I called SmithBrothers pushrods and got a complete set of adjusters with quality locking nuts for around $85. I simply ran a tap thru to chase/clean the threads, and installed.