A while ago (about a year, or so) I posted a query with a problem of my 65 D200 having a "popping" in the exhaust. I did vacuum, compression and timing checks (all o,rebuilt the carb and bought/swapped a new ECU, with no change. Next I pulled plug wires 1 at a time and found 2 cylinders suspect. I repalced the spark plugs and checked resistance in the plug wires; it ran a little better, but still had the persistant "popping". I was frustrated and made these attempts over the course of the last year. Finally, I did the plug wire pull again, same 2 cylinders and replaced these 2 plug wires. IT WORKED. The truck now runs like a top.

Thanks to all for suggestions and don't trust a resistance reading (or continuity) in plug wires. By the way, the plug wires had less than 12,000 miles on them and still looked like new.

Thanks again to all who provided input.