The Pentek 154737 is the correct replacement mounting boss cap for the following housings:
The Pentek 154737 3/8" 3G MB Filter Housing Cap W/O PR is a replacement mounting boss cap for all 3G housings. This Pentek filter housing cap is constructed with durable polypropylene and has an 3/8" inlet NPT/outlet connection. This filter housing lid arrives in a blue finish and does not feature a pressure relief valve. In order to wall mount this MB cap you will require an MC-1A bracket, which is not included.
Pentek 154737 3/8" 3G MB Filter Housing Cap W/O PR specifications: