5.9 leak at thermostat housing

[ColoradoCummins]

Greetings bus gurus! My 5.9 developed a coolant leak last weekend, and I'm looking for some advice/expertise. I have attached a few photos for reference.
[IMG]

[/IMG]
At first I thought (was really hoping) the leak was just the 90 hose at the thermostat housing, but I have replaced that to find out that it is actually the housing itself that has a crack. Has anyone else encountered this issue?

I have purchased:
1 - new 180F thermostat
1 - new housing
1 - new bolts
1 - weird ass gasket
1 - new serp belt

A few questions:
1. Should I use RTV in addition to the gasket to ensure a leakproof seal between the housing, hoist bracket, and motor? (what a crazy design....)
2. I'm gonna be right there, what about replacing the alternator as well?
3. Any other advise, thoughts?

Thx!

[ColoradoCummins]

Here's the parts breakdown from Cummins Quickserve. Part #2 is literally a rubber cylinder that I guess makes the seal between the motor and thermostat housing. It bridges the gap that the hoist hook makes.....