Floor support fitment to front frame rail

[69Mach1 M code 20]

I purchased new floor supports from NPD. I noticed that they have quite a bit of clearance when positioned over the rear of the original front frame rails. I would guess about 1/8th inch side to side.

Is this normal?

If not, I'm planning on using shims on each side to take up the clearance(?) Has anyone had a similar scenario? 

[latoracing 256]

I have ran into the replacement floor supports varying in width, and some parts I wouldn't install because they were ridiculously too wide.  Check the dimensions between the new parts and the originals to see if or how much wider the replacement parts are. The frame rail is in two pieces and can be modified to fit a little wider floor support without using shims. 

[69Mach1 M code 20]

The lower section of the frame rail was completely rusted to the old floor support and the adjacent material was deeply pitted and pretty thin. I was able to get a pair of calipers on the upper section of the frame rail that's still in good shape. 

I threw the calipers on the new floor support as well and found part of the problem. It looks like there is a bit of a draft angle from bottom to top due to forming, about 0.100" or so.  The inside width at the bottom of the floor support is about the same as the top of the frame rail so I should be good to go. I may remove the draft angle in the press to square things up.