Flathead Monster is a strain from the personal collection of a gentleman referred to as Spudleaf Willie (Bill Malin) known for his love of spud (or potato) leaf tomatoes. Spudakee is just one of many fine maters he has come up with.
I think the name was actually changed to Orange Orangutan :)
They can be purchased from here(I'm not affiliated with them) https://www.mariannasheirloomseeds.com/heirloom-seeds-catalog/mariseeds-heirloom-tomato-seeds/yellow-orange-tomatoes/flathead-monster-orange-detail.html
I'm growing some tomato varieties this year which include Rutgers, Malachite Box, Gail, Flathead Monster Orange, Not Purple Strawberry, Indian Stripe Burson Strain, Berkley Tie Dye Pink, Gold Medal, Cherry Brandywine, Earl's Faux, Mckinley, Barlow Jap and a few others.