The Mack B-60, a model from the Mack B-series trucks, could be equipped with a variety of engines, including gasoline and diesel options. A common gasoline engine found in the B-60 was a 464 cubic inch (7.6L) inline-six cylinder engine, capable of producing around 185 horsepower. The Mack B-series, which the B-60 was a part of, was known for its diverse engine options, encompassing both gasoline and diesel engines. Some of the other engine options available in the B-series trucks included diesel engines like the 8.4L I6, 11.0L Thermodyne I6, and the 14.0L Cummins NTC I6. Essentially, the specific engine used in a Mack B-60 would depend on the specific configuration and year of manufacture. i dont think you will find a engine that will fit in that time frame, but Auslowe does make a E 7 Mack 6 cylinder that you can get from them. they also have others to choose from..https://www.auslowe.com.au/shop/mack-e7-6-cylinder/E7