Cessna 348 0-2TT
I was straightening out my aviation book shelf last night and didn't realize what this manual actual was for. I've had it for years and just thought it was for the standard Cessna O-2.
The manual is dated November 1968.
The performance difference to a standard 0-2 is quite remarkable. The manual specs it out with Allison 250-B15 Turbo Props. It also has a 31% larger wing area over the 0-2.
Pretty cool little aircraft.