Mareks Disease from The Poultry Site
Sandhill Vet Services
Note that I'm assuming it was Marek's because he also had the ocular and the cutaneous forms.
Thanks @Eggcessive and @casportpony Those pics help a lot. Really this liver looks most like the leukosis one and the symptoms from wikipedia match very well. "Symptoms include enlargement of abdomen, bursa, weight loss, weakness and emaciation, and depression. The disease is more likely to affect chicken around five to eight months of age who are more vulnerable. Green diarrhea tends to develops at the terminal stage."
The time line is the same as my birds, along with weightloss weakness and emaciation, tho these are not noticiable until the end.
My Edible Garden http://edible-garden.blogspot.com/ Current bird count; about 40 + or - a few chickens, 7 ducks; Easter Eggers, Olive eggers, Buff Orpingtons, Ameraucana, Black Copper Marans, Buff Plymouth Rocks, Muscovy and Welsh Harlequin ducks.