Yes--there's a King Tut that is a varigated yellow/gray.
I looked at King Tut, but I didn't see one. Do you happen to know the name or number?
You can also thread your machine with 2 threads. One Yellow, one gray. Thread the machine as though you do with 1 thread and put both threads into the eye of the needle. This does work, I have done it.
I will be giving this a try - thanks!