If the yoke does not have the milled groove you will not reuse the O-Ring. Our supplier has a couple versions of the yoke that are the same other than the O-ring groove.
Odds are the codes are for an Evap leak as the drip line fitting may not seal well enough to keep it happy. The fuel vapor may cause it to deteriorate over time as well.
Personally I would do the RCV fronts and some upgraded ball joints while they are in there. The ball joints are a known weak point on the JL's and will need replacement sooner than later. Currently the Dynatrac ones are the way to go and use a retaining clip on the top to ensure they can not get...