I did the same as Scratchn. The OE ones have a thin groove lengthwise alongside the OD from end to end possibly to let air excape so it will seat firmly in place either that or it is a mfr tool mark that is insignificant as far as functioning. Either way I added the groove/no issues. hand the p rod to your parts guy & have him cut a snip of whatever ID slips firmly on the round nub rod end just a hair shorter than the length of the recessed groove on the p rod (it'll likely be a freebe) & you're set