Hi.
Long story short I just bought a pretty clean 1998 XJ and found out that the driver side floor is rusted out. I bought a OEM full length floor pan From Key Parts and Im in the process of cutting the original floor to fit the new pan.

Im having trouble understanding how I should cut the rear section, that is, just before the rear seat riser. Do I need to keep a strip of the old floor in order to seat my new pan on it?
The pan has a small raised section at the back so that makes me think I should keep a bit of the old floor there.
Right now, the new pan sits a bit too high, it needs to go down about 3/4in to make contact with the frame rails
Here are some pictures (sorry for the poor quality).

How much I have cut as of right now.

The pan in its place. It sits about 1/2in too high right now

Where the pan sits at the rear. It also seems to be a bit too far in the front so I probably will have to shorten it a bit

 

I have never done an xj but on other cars I've done they had spot welds to take the old pans out. Cars that didn't have the spot welds I used a lipping pneumatic tool. I have one from harbor freight that I have used for years. I found this video at eastwood that will show you what I'm talking about. https://www.eastwood.com/perfect-pan...vX2FmPvF8W9xMj

 

When I did mine I bought all 4 separate pans but same brand as yours. I had to shorten mine think it was like a inch or so also had to cut some relief in them and pound them into shape on some of the curves. Mine stopped few inches in front of the rear set riser but I still had to cut out a section of it to repair some rust and weld it back. Any chance shorting them or ....reforming them with some relief cuts and a hammer would help?...Just a suggestion...