O. K. On the headgaskets, the 158850 was the standard head gasket for the 1750 gas engines. The 159320-As was developed to solve some head gasket problems with the B &amp; C 1800 diesel engines. I can fax you a copy of the service bulletin. I will look up the specs and it will probably be tomorrow. I go to the eye doctor today and by the time they get done taking pictures and all that other stuff with my eye I will not care about or be able to see anything the rest of today.