[Walt Dupont--Me.]

I think some big trucks used the Merc engine but it could have been replaced with a Merc engine. OR, It could be a Ford engine with the 3-3/4 crank and someone put Merc heads on it. The no. on the back don't mean anything. The rods are all the same, the wrist are in a different location. You'll never know until you get heads off and measure the stroke if it's got a merc crank. The merc heads are useless for us engine builders unless your using a big supercharger. They have big chambers. The best stock heads for the 8BA style engine is the EAB heads. Walt