Has anyone actually replaced these when taking off and then putting back on the rear combination lamps?

The FSM states in bold "Caution: Seal Packing cannot be reused". It calls for taking off the old seal packing and putting on new seal packing anytime you take out the rear lamp assembly.

It looks like the seal packing goes in front of the 3 nuts, so there are 3 packing seals on each lamp.

I recently had my tailights removed for paintless dent removal on my rear quarter panels, and local dealer did not have seal packing in stock, so the paintless dent repair tech just put back the lamps w/out new packing seals.

Does anyone know the part number of the packing seal or where it can be ordered from, or if it is really necessary to replace per the FSM?

Also, is it normal for there to be a slight gap between the lamp assembly and the bumper? The lamps are in there tight, but there is a little clearance (not perfectly pressed together). Not sure if there is a preffered method of putting back the lamps to ensure the tightest fit (order/torque of nut tightening). Dealer said the lamps visually looked ok resinstalled.