Engine/Transmission (1994 - 1998) 95' 160HP pump with 181's, do I need to keep the copper washer, or discard?

[Fordiesel69]

All the threads talk about the 160 pump having the copper washer under the DV. If I swap out the 131 dv's for 181's will I need to use a copper washer or do I just remove them? I am not sure of the year the 181's came out of. Still waiting to hear back from the person I bought them from.