Jorrell,

I said cap but its actually more like a threaded plug with an allen wrench head. On my 1990 240 all 3 u-joints had them. They weren't on the caps but in between. A picture here is worth a thousand words and I know there is one floating around on the BB. I also remember reading that all u-joints might not have them. I was changing out the center driveshaft bearing and deceided it would be a good time to add the zerks.