I have 2 slip clutches for the tractors, one is 1 1/8"? to 1 3/8"? spline, and the other is just 1 3/8-1 3/8" and i have lost both of the roll pins for them

i was just wondering if you HAVE to have a ROLL pin in there? i know that they are hollow blah blah blah so they can get grease, but local hardware stores dont' have the right sized roll pins, they are too short, but are only bout 3/4 the length of the "correct" one... but would a shorter one work? apposed to using a regular pin the right length? (no hole in middle or anything)
just want some opions from people who know before i might ruin somthing....
Thanks for any help/advice
Johnny