Below is a link for looks only, the whole set up as one molded unit is in the Dyers catalog not appearing in the on line store...Their part# is [b]Part#88-9118 the [b]manufacturer part# is RF911VP, coded as [b]Ivory,1/cd "single count" or 88-8869, Mfg part# RF911, for 6.69 Ivory, Bulk 5.39 if ordered by multiples. This is the one you have.
[b]Identical in looks is one which screws together, the barb part in the back is a threaded fitting entering in the back of the scoop with lid, as a two piece unit it screws one into the other locking by threaded coupling into place firmly sandwiching the fiberglass wall, no need of screws like the old style you have. These part numbers are below the address of this vendor...he has a large catalog you might request.
Dyers RV Supplies
They also run an Ebay store.
On Page 548 of the 2008 catalog.
Outside part, one Ivory, one White.
Their Part# 88-8836 manufacturer part# MA-402PW,PW price 3.09
Their part# 88-8813 manufacturer part# MA-403CW,CW price 3.09
Their part# 88-8818 manufacturer part# 741016, barb adapter price 1.89
A pic of the two part model is seen below.
Happy Camping, Safe Journeys
I'm missing the 1/2 moon cover for the fresh water fill port.