What do I need to use to get the rest of whatever this is out of the thing.... It's a 99 with a v10 in it?

 

You need to back flush it. Prestone sells a kit.

 

With that much crap in it, I would just replace it.

 

Yeah I was thinking replacement would be better too.. I hate it when people neglect vehicles I swear!!!

 

WTH? Definitely replace and then flush. Better disconnect the heater hoses and flush the heater core. Also remove the thermostat and use the heater hoses to flush the block. Replace with new thermostat.

 

This is a prime example why I tell people to flush the cooling system every three years. A little preventative maintenance goes a long way. That fluid also looks like dissimilar coolants were mixed, thereby forming the mud.