The floor to frame heights can be different when comparing different cars. It depends on how high the suspension is riding, tire heights, etc. The important number is the difference between the two measured points on each car. That measurement should be relatively the same between two cars, no matter how high off the ground the frame is sitting.

 

hey bgss350,i got your second set of measurements and they are really close to my measurements.doesn't it make you stop and think about the measurements from that diagram.if you take the diagram measurements "x"(6 15/16)and measurement "a"(15 3/4)the difference is 8 13/16".The difference i have between those measurements now is about 12" and yours should be about 12" also. so if i go by the diagram i would have to lower the rear part of my rail about 3" which would be way too much.Am i over thinking this or what.let me know what you think.

 

For the diagram meas "x" of 6 15/16 I have 8 3/4, a diff of 1 13/16
for the diagram "a" meas of 15 3/4 I have 18 1/2, a diff of 2 3/4
The diagram diff between these is = 8 13/16 (as you stated)
My meas diff's are = 9 3/4 Just about 1 in of difference.
Meas "x" I took is from ground to underbody mount location of front part of leaf, not the leaf itself or bolt head. In the diagram it looks like this area has a "rail", mine looks like part of the car underbody, not rail looking like the rear attachment point in the diag. Let's confirm we are talking about the same locations.

 

well i decided to torcher myself and take the frame rails out and reposition them in the right spot(they were partial rails not full rails).it turns out they weren't in the right spot and now i have about 3/8" of an inch gap where the rail mounts by the shock mounting hole right where the rail bends down to go to the front of car.the gap only goes for about 3-4 inches and i'm thinking about shimming it(can't think of any other way around it).does anyone have any thoughts on this.by the way,the quarters line up perfect now along with all rear body parts.thanks again for everyones help.