Body measurements

[streetbird]

Simple question but complicated to formulate.
I am working on a jig for my car and I dont know how to take the diagonal.
Do I have to transpose it on the floor with plomb bob to measure it or simply measure it from hole to hole and dont take in consideration the difference in height of the hole?

Measurements
http://1stgencamaro.net/frame.htm

[makoshark]

I recommend using plumb bobs and marking a line on the floor and measuring from those points. You can try to measure just from hole to hole, but it doesn't always work well if the two holes are not on the same plane.

[streetbird]

thx, its exactly what I want to know.

[streetbird]

Note for other user of this chart, F measurements is 75 7/8, 76 as indicated is off. The line G and H cross F at 75 7/8 not 76.
I take an other chart to get that measurement and its more accurate than this one.