'67 Dart with '68 idler arm?

67 only idler arm has ball socket makeup on both ends. All 68 and later has a bolt through 2 steel ears at the K member end. Back when these were daily drivers and bumping curbs when parallel parking or sliding on ice into curbs, the 67 idler arm attachment proved inadequate. Hard side walls of bias ply tires wouldn't absorb all of every impact.
The 67 only part is available today from multiple vendors. Upgrade requires welding a different 2 ear clip onto the K. Your call.
Additional... I cant say if the 67 idler arm will still attach to your k member. Someone might have drilled the hole to accept the through bolt.