Please check the boxes for the options that you would like to add. Leave all boxes unchecked for unit only.
TCM NEW MAGNETOS S4LN 20(RH) /S4LN (LH)
You are correct, only S4LN-21 has an impulse coupling. S4LN-20 does not.
Yes, these are new units priced as each.
Both mags are LEFT rotation, LH and RH are referring to which side of the engine they are installed.