Originally Posted by 300MAG
From what the op posted it doesn't sound like it can flip forward if someone is sitting in the seat. You need to flip the bottom seat up for the seat back to become disengaged.
I totally agree but I'm just looking at it from a legal point of view. By altering the installation of the seat (even with a washer) you have effectively "altered" the construction/installation of a factory part. Even though the seat couldn't come forward in a collision, I'd have to assume an insurance adjuster would try his/her hardest to win the case against the owner/driver of the truck.
I like what he did...just wondering if altering the installation has any bearing from a legal stand-point.
As for taking away headroom - I think that would be minimal (if even noticeable).