[Zmagnette] Engine Clatter & pressure drop

[Richard Greenberg]

Hi all,
      This is about my TD, but I bet you folks can help. 
      I decided to drive the TD, instead of my Magnette, to our British car club's annual BBQ.  About 25 miles out, running at about 50 mph uphill but not too hot, the engine started clattering and the oil pressure suddenly dropped to about 5 psi.  I had the poor car carried home.
      Any ideas about what happened? Rod bearing wiped out? Broken rocker arm?
      If it is one of those things, should I just make the repair, or is it time to have the whole engine rejuvenated?
Thanks,
Rick