I just purchased a 1997 Exlorer XLT with a 6 cyl. egine. Seller said the egine was the SOHC, but all that is stamped on top of the block is 4.0 EFI. Wouldn't SOHC be stamped on the block if it was indeed one? The egine does seem to have a lot more power than a 1996 6cyl. I test drove, so I'm not...