Mugsy, don't bother with the dishwasher. Put them in a plastic trash bag and spray them really, really good with oven cleaner (like Easy-Off). Seal the bag and let them sit overnight. The next day, you should be able to wash off all the crud very, very easily. I do this all the time with the porcelain-coated grates for my gas stovetop and my steel oven racks.
"As a girl I had zero interest in the stove." - Julia Child
This is real inspiration. Look what Julia became!