Middle Seat Shoulder Belts

[MoroneSaxatilis]

Does anyone know what year they started putting a shoulder belt in the middle seat of the rear seats in GMC Yukons. Also wondering if someone does know the year if those seats will swap with a 98 without too much trouble. Would seem to be easier to just swap out the rear seats as opposed to installing a shoulder harness or having to buy a booster seat for a year or two's worth of use.

Thanks, and sorry if this has been discussed already!

1998 Yukon SLT.