I figured it out. Cutting it out from the bottom would be just as difficult. Here is what I found out. There is a rear channel that spans the back of the cab. The back of the seat risor is welded to this channel. This is all covered by the wood for the back of the suburban. I used a Sawsall to cut the seat riser loose from the channel. You will notice that I also cut the top trim peice as well thinking that would help (which it did not). i will need to remake one anyway as this one had some bad rust through.

Here are some pics.

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If you look closly you can see where the metal seta flange goes underf the wood and is welded to the back channel.

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In the end I won. Now I can repair the edges of the seat riser and put new floors in. I will make my own floors as the kits that are out required work to weld up holes for stuff that I dont need for my application.

Marc