When I stripped mine I had the last 5 of the engine number written in a white pen on the floor pan..wonder what that was all about. I see that yours has also rusted on the seat mounting holes.. Are you going to replace the floor pan section or cut out plate etc...mine wasnt as rusted as that so I cut out a square and flushed welded a new bit of metal in and puddle welded (think thats the term) three welds to hold the seat mount to the floor pan under the car