Ok this might be a dumb ? But is there a difference between the right and left head on a 3.0? I noticed that one of the heads had a #1 and #5 in the combustion chamber side of the head. Does this mean that is for the right side of the engine? meaning #1 #3 #5 cylinders?

When I pulled the heads off, the head with the #1 and #5 was on the left side of the engine.

The #1 and #5 is cast in the head it's not just scribed on it.

'94 3.0

 

When I took my 3.0 heads off, I didn't see a difference, but I am by no means an expert. It seemed that even the exterior points for mounting accesories, etc, were matched. When they got all cleaned up, there was no way to tell the difference except for the fact that one of my heads had a broken bolt hole, which I knew was from the passenger side.

I believe the stamped numbers refer back to when the engine was manufactured. Something about the original tolerances and piston sizes. But I thought those numbers were stamped on the block, not head.