Not surprising that they don't match up. The critical thing would be the position where the body mount bolts go.I believe the Factory Assembly Manual has dimensional information for the floor of the body. I know it has locations of bolt holes, etc on a side view. Check the FAM for those critical dimensions.

For the angle of the tabs on the end of the body mount channel, it's likely going to be "beat to fit - paint to match".
That's going to be my task come next spring when I pull the body off to repair the rusted out floor.


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.