I originally had a head gasket leak and decided to do both sides. Real PIA but got it done. 20 miles into test drive I feel a thump and massive misfire. Get it home and discovered that a lasher locked causing valve stem to break and cascaded into exhaust thrust up my intake.
I listened to Ford as far as not using RTV last time, but looking at the 20 mile headgasket (yes I am rebuilding) I'm not sure

20 miles. Block side