OK I found a picture (and it wasn't easy) of that stupid Saleen thermostat housing.......
From what it looks like, obviously the think 3/4 fitting goes to the Degas tank... Which I have it doing there now.
However, the coolant opening facing you when you look at the photo (the one I put a coolant expander cap in) seems to go to the water inlet on the block.
The coolant opening on the bottom of the housing (the one facing the guys palm in the picture) appears to go to the outlet on the water crossover on the top of the block (next to the alternator)
The top coolant opening on the top of the housing (if looking at the picture)... and also the area where the top of the thermostat is housed..... would seem to go to the lower radiator fitting.
So what I am gathering from this (and I think I asked this originally), is that this stupid (for lack of a better word) housing from the Saleen allows coolant to bypass the thermostat. Coolant is pumped in from the water pump (coolant opening on the lower drives side of block, the water pump then circulates the coolant through the block and out of the coolant bypass (On top of the block next to alternator).... it can keep circulating freely because its bypassing the thermostat. Once it gets hot enough, the thermostat opens and coolant can then flow through to the lower drivers side of the radiator and (up?) to the upper radiator hose and then re-enter the engine once cooled through the other side (passenger) bypass inlet on the top of the block next to the alternator.
This to me seems to be overly complex. However, even in this design, the degas tank is tied directly into the coolant that is circulating around through the bypass.... gaining temperature awaiting the thermostat to open.... and coolant never boiled out of the Saleen the 2 weeks I drove it stock. Im guessing, even though I have adapted it to just be an inlet for my degas bottle inline on the lower radiator hose, it should still work.
Thoughts on this? LOL BTW, it seems that there are many different styles, flows and thermostat configurations for the 2005 Mustang (depending if you have a Saleen, GT, V6, Cobra, Shelby, Etc) Confusing as all Heck (yes.... heck is what I will go with).