Hi I'm new here also new to truck diesel. I work on V12 twin turbo detroit diesel on the Marine Corps M88. Dont know anout trucks though. I just bought this F250 7.3 It has 175,000. I was told it was missing so i took it to Ford to verify. I figured an injector. They told me their diagnostic said my #1 injector but wanted to do a compression test on that cylinder. I didnt want to pay the money they were asking plus I want to learn how to do it myself. My question is can a compression test be done on either the glow plug or injector hole? Any advice would be appreciated.