just replaced the drivers side floor pan have the sub frame brace that looks good.put the seat pan over it and the back of it wont sit flat for welding.is this a normal problem when using floor pans from one company and other parts from another.looks like im going to have to cut the ledge that sits in the middle of the sub frame bracket i think that's what keeping it from sitting flat ?any ideas what i have to do to fix this.i still have the passenger side to do once i am done on the drivers side

 

It is hard to say without seeing it, but it is pretty common to use self-taping screws into the sheet metal to hold the metal flat for tacking in place. Aftermarket panels tend to stress in them and do not stay flat. I don't think I have ever had a aftermarket panel fit without clamps or screws. I have even tack and area and then had to pound on the sheet metal then tack another area and so on. .

 

Did you have the subframe connectors already installed with the old floors? Some of the weld in connectors require you to notch out the very rear of the back floor to clear the connectors, then you weld the floor around and to the subframe connector.