The original Williams part number is 5792-12535-05, which corresponds to a Panduit CT-100F22-5. You need a "through" connector, not an "end" connector (which is what Marco sells) when the wires continue through the connector, as is the case for the one you show in your picture. It may be possible to cut through the nylon web on the side of an "end" connector housing to make it work as a "through" connector.
You could buy a couple of CT100F22-10-T connectors from a seller on eBay and cut them up to make a 5-position connector (search for item 390433363667).
There's also a chance I might have one of these at home; PM me and I'll check my parts stash.
Pleasanton, CA
