https://www.truck-manuals.net/mack/ 256 METRIC CONVERSIONS METRIC CONVERSIONS Note: Use all tools on the fasteners they were made to be used on. Use metric tools on Sl metric units only. Never try to use metric tools on U.S. standard fasteners or U.S. standard tools on Sl metric units.
CAUTION Potential external/internal thread mismatch condition(s) may occur with certain metric thread-inch thread fastener combinations, and with fastener combinations involving incompatible metric fastener systems. A given thread mismatch condition can result in thread stripping and/or assembly weakness leading to potential service failure, thereby rendering a vehicle non-operational and/or unsafe for operation. The specific external/internal thread combinations from which such problems can result are identified and set forth in Maintenance and Lubrication Manual
