I have just been reading the post on which bits are called tappets and it reminded me of when I broke down on my A10 in Preston in about 1972, for some reason I had to remove the rocker box, so re-fitting without the pushrod guide tool was a heck of a job, I searched for and found half a dozen lollypop sticks (these and matchsticks were as common as chewing gum remnants are now) these were used to hold the rods in place as I lowered the rocker box.... happy days and fond memories!