there is no vendor that sells a SYE kit for the sidekick yet. i just spoke to brent today and he says he's working on one, but it's not in production yet.
are you sure you have the suspension set up right? i have the very first production kit on my sidekick and it's been driven daily for the last year and half and wheeled hard and i'v had no trouble yet. are you sure that the machined surface of the slip part doesent have a bad spot on it? if it happens everytime immediatly after you drive it , i would say there is a burr on the slip part of the shaft.
hope ya get it figured out
jason