Henry,
The one seacoast mortar that I have actually seen is in St. Michael's Cemetary in Springfield, MA. It is number 1188. That number is engraved on the muzzle and embossed on the upper right side of the barrel. The other engraving on the muzzle includes "P., 17124 lbs, J.M.B., FORT PITT. P.A.
The plaque located on the back underneath the barrel appears to be made of marble, and reads; "HONOR THE DEAD" "THIS MEMORIAL IS HERE PLACED BY E.K. WILCOX POST 16, DEPARTMENT OF MASS. G.A.R. TO MARK THE LAST RESTING PLACE OF BRAVE MEN WHO IN 1861-5 OFFERED THEIR LIVES FOR THE HONOR AND INTEGRITY OF THE NATION." The plaque is dirty and cracked. I and my camp of Sons of Union Veteran's are exploring plans to renovate this memorial. I could use a paint job and perhaps a concrete base. The gun now sets on a layer of bricks that is deteriorating.
I have heard that this piece is one of only three that are still in existence.
I am working on registering this monument with the Sons of Union Memorials Committee and would like as much information as I can find about this piece.
Thanks for the reply.