I've just purchased 88 D250 with a 318 and no OD and was wondering what gear sets where available in these trucks?
My 90 D250 has 3.90s and I was hoping for a 'better' set.
ALSO, how can you tell a visible difference between a 318 and a 360?

 

Driver's side of the engine, towards the back, under the exhaust manifold there will be a pad with the displacement stamped on it. That's the easy way.

What ratios are available for the rear axle (dana 60, should be anyway)? There's a ton. What do you mean by "better" Better for freeway cruising or better for accellerating?

 

Will the displacement be in litres(5.7) or inches(360)?

Better for Hiway, the 90 has 3.90s, so was hopin, 3.55 or 3.00

 

It'll be in inches. Don't know if you were just grabbing numbers but the 360 is a 5.9, but it'll clearly be stamped with either 318 or 360. My uncle thought he had a 318 in his van but somebody swapped in a 360 somewhere along the line.

If the D250 was a camper/towing setup it'll probably have 4.10's like my W250. Commonly available ratios range from 3.54 on up to 7.17:1

You would think numerically lower ratios would be available, but maybe not due to the large ring gear diameter.

 

If I put 4.10's in mine, what else do I need to do besides the gear swap?

 

You'll either need a speedo cable reduction box or the correct speedo cable gear. Don't ask me what gear goes to what ratio. When I went with 35" tires I just had a cable adapter box put in to correct the speedo/odo.

 

My gear ratio is a little weird, it says its a 3:17. I've never heard of that gear ratio before.