I recently purchased an early production date 1997 F-150 with 83K miles on the 4.2 motor. I noticed coolant on my garage floor just about the same time I found this site. Thanks to all of you who have already experienced this problem. Knowing what the problem is, is half the battle. I bought the intake gaskets, timing cover gasket and a timing set from a Ford dealer on the internet. Parts were cheaper than Autozone or Advance. It took me a little longer than Ford allows for the job. I took my time and cleaned all the gasket surfaces thoroughly before re-assembly. I discovered evidence of slight coolant leaks on both heads. Fortunately, I did not experience a hydrolock. Truck runs good with no leaks.
Without the posts on this and WWW.Leakingfords.com I would not have tackled this big a job. Thanks again to all you Ford veterans.