Thanks for posting photos of your excellent original one owner '66 salty531. You just happened to buy one of the most desirable models in the '60-'66 series. You deserve a lot credit keeping and preserving this truck over the years. Lets not spoil this little gem on just over what a shop person claims to have, photos will resolve that issue. I believe in the end, it will all boil down to miscommunication. Brad54 hit on the double roller timing chain, which may be the real heart of the matter. The 327 option in '65 and '66 pickups was a modified truck engine not a car 327 engine. Most mechanics are car engine mechanics, not truck engine mechanics and may not be familiar different features. Photo of timing chain from '63 truck shop manual. Mid year '66 offering of the 327 in C 10 from engineering manual. So, it would be logical this C10 was special ordered in '65 with a 327 (220 hp version used in '65and '66 C 20-30's ) because it wasn't available as a standard option at that time. Please check out the "most original in existence" thread ,
http://67-72chevytrucks.com/vboard/s...+existanceyour your truck should be added to it!