I was at an antique engine show yesterday and a fellow there was selling new 6.5 mil. surplus engines. I'm needing a new engine for my '93 Chevy 2500 2wd, and at $2500, these are considerably cheaper than other sources I've looked up. I asked him if his 6.5 engines had the NA comp. ratio or the turbo comp. ratio and he insisted they were set up for turbo operation. Has anybody had any experience with one of these mil. surplus engines or knows what other identifying characteristics I can check to see if it's an NA engine? I seem to remember the comp. ratio on my old '85 6.2 was 21 to 1, and on my '93 6.5 TD it's 19 to 1. What block casting numbers should I look for and where are they located? Any help would be appreciated.