Anyone know if a 426 left engine case cover is the same bolt pattern and size as a 450(the one with the oil fill hole)? I've got a Graves Oil/Air separator tank kit that I thought I could make work on my 426. But the 426 timing plug and 450 oil fill are not the same. If i can't get a 450 left case cover to work I'll have to find a smaller fitting to then drill and tap my own hole in the case cover. Then again, finding a left side case cover for a 450 may be about as hard as getting the fitting and drilling the hole in the 426 cover. Just wondering about options really.