This will be long, as I have several questions.I am brand new to diesel motors, but have a been turning my own wrenches for quite a few years. I just purchased a 1984 Chevy military M1010 with 6.2L diesel.( Chevy 1 ton, 6.2l, th400, np 208, 60 front (open). 14bff rear, w/ detroit , 4.56 gears ) The truck was a military air field ambulance in VA., and from everything I have seen , including the paperwork it has 18K original miles ! Having looked at a bunch of CUCV trucks I can say this on is in great shape.
Ok, the questions.

1. Where to start on motor? ( IE: servicing and things to look for ) Motor does not smoke, leak, and starts right up cold. Does want to idle high sometimes on start up.

2. Best manuals to get for motor? (Have Haynes tech book for diesels and general Chevy year series manual.)

3. Would love to get a tad more performance from engine but do not want to burn it up. I dont tow much, and this truck will live mainly on the street. Suggestions? ( Banks ?) I am looking for reliability first.

4. It is geared 4.56, and with the 31" tires that came on it about 55 is max speed. Tire size to get diesel back into non-race car mode? 35's maybe?

5. What is the appropriate rpm for a 6.2l at 55 mph ?

Okay .... I will be quite for now.

Thanks, Chris

Welcome, 35 inch tires would be a good start. 4.56 gears are too low for this engine unless a person is limiting speed to around 55 mph. 315 75 r16 is a good size to run on your stock rims.

6.2's are great engines with some minor problems. Early versions do tend to fail head gaskets, especially if the engine is overheated. Newer head gasket designs are far better.

Keep the oil changed with a good quality diesel 15w40 at about 3000 mile intervals and run it for 300,000 miles. Also keep the fuel filters changed. :cool2:

Idling high once in a while is normal, my 85 does the same thing, the fast idle is temp. controlled. I don't have a tach but my 85 burb has 3.73s out back and @ 55 its under 2 4 sure and reds around 4 this im sure of bc thats what the limiter is usually set to.