Your old power supply was held in the chassis with two screws; the new power supply will require four screws arranged in a square pattern. You should receive the power supply along with an insulation sheet (part# 140054); the insulation sheet can be used as a template for marking the new holes that will need to be drilled into the chassis because it has four equivalent holes in the same location as that of the power supply.  Once the holes are drilled; you will want to raise the power supply off of the chassis floor of the MS-440; this being a double rack space (2RU) station allows more clearance than the single rack space station so the non conductive (plastic) standoffs that you use can be up to ½ inch if you wish.
Your current power harness has quick disconnect style spade lugs on both the AC and DC sides; these will need to be cut off and replaced with a connector that is designed for the new power supply. The Clear-Com part numbers for the insulation displacement connectors (IDC) are 210360 (5 pin housing) & 210314 (6 pin housing).  The wires are pressed into the connectors for electrical contact; no pin crimping needed.  The 6 pin housing goes on the DC side; the 5 pin housing on the AC side.  The DC power harness may need to be lengthened depending on the orientation of the power supply since the in & outs are on opposite sides of the power supply