How many miles is on your 1st gen?
#21
My odometer broke a few years ago at 193,000. Since then I've rebuilt the transmission, and while it was out checked the end play in the crank to get an idea of what kind of shape the main bearings are in. .011" play, the cummins book says .008-.018" is suitable for a rebuild, I think she's good to go for a while!
#22