IIRC all '87 trucks have the later style IP timing gear housing...I've seen engines that were definitely 6.9l's that had the later housing, so I'm not surprised by this.sure thats a 6.9 sure looks like a 7.3 ip mount to me

606K? surely a type-o...

is ther any outher way to tell a 6.9 from a 7.3 with out opening it up