Timber Jack I don't know how to search the archives to find the threads but I'll tell you how I cured the identical problem on a 2004 460 that I bought new.
At about 150,000 miles it started puking coolant like yours is doing. I replaced screens, thermostats, and even the radiator and all hoses to no avail. Problem got worse instead of better. I fought it 2 years or so.
In desperation for my last shot I went to the bone yard and got a large capacity single compartment aluminum reservoir tank and replaced the original 2 tank Mack set up.
I only fill the reservoir to half full and replaced the radiator cap with a 10 pound cap instead of the 16 pound that was recommended.
Over 1 millions miles later he has never puked coolant again after the switched reservoir.
The stories should be archived here written by JerryB and begun.