I decided to go with the Sullivan metal push rods and clevises. I bought both the 4-40 size and the 2-56 size. The 4-40 seemed a little bulky and was binding in the outer protective tube. The 2-56 seems to work perfectly. Having said that - there is a part in the kit called a "rubber nut." It is just a piece of heavy black tubing about 1/8" O.D., 3/32" I.D. and 1" in length. Does anybody know what this is for?