The 3M CUNO DP1 is the correct assembly that uses the following replacement cartridges:
The 3M CUNO Dual Port Single Manifold Assembly contains 3/4" MNPT inlets and outlets. This single head dual outlet assembly is also known as part number 6228603 and DP1. This CUNO valve-in-head assembly features a dual port-single manifold assembly, series plumbed, shut-off valve, pressure gauge and a "T" connection for inhibiting scale.
3M CUNO Single Manifold Assembly Specifications:
The CUNO DP1 Manifold Assembly should not be installed on a hot water supply line. The maximum operating water temperature of this assembly is 100 degrees Fahrenheit (37.8 degrees Celsius). Be sure to remove your cartridge filter when the temperatures are expected to drop below 40 degrees Fahrenheit (4.4 degrees Celsius).