Have a 3.4 6cyl. that I am rebuilding, when I tore the engine down it had a single piece rear crankshaft seal and then in the rear main cap and block it also had another seal in the two grooves in the cap and the block. I have been unable to locate the seal that goes in the two grooves. I have been told the one piece seal takes the place of the double two piece seal. I do not feel comfotable putting it back together like that! With that cheap one pieces seal.