MOTM

Does anyone know the part number for the little plastic dust cover
for the AMP MTA156 4-position feed-thru connector for 18AWG wire??
The Digikey part number for the connector is A31374-ND, but I can't
seem to find the dust cover.  The dust cover for the closed-end
connectors does not fit.  This would be for a connector one might use
to power a daughterboard added to an MOTM module -- the wires go in
one side and continue out the other.

Thanks :)