Hi, I ordered a new set of seats for my 97 PII (Thanks Basscat for the very quick turnaround). I have the old seats out and ready to install the new ones but I have a question about the seat backs. I noticed they were not on the bottom lip of the boat. I am thinking the are close to the thickness of a 2X4 from the bottom. How did you measure the height of the seat backs? Would 2X4 shims be correct? Any help appreciated.