Yes, sleeves are available and that is how I do my diesel rebuilds. The place to look for wear on the pistons is the ring land area, and the wrist pin hole.

A list of items that I always replace during a high mile rebuild on a diesel:
obviously the rings, bearings, gaskets, timing chain & tensioner, valve guides & seals, crank gear and front seal sleeve, oil cooler hoses, vac diaphragm,water pump, I'm sure there's a couple of things I over looked



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