frame dimensions don't exist

[c30]

I am currently in the process of converting a 71 c20 long bed frame to a k10 short bed.
I have searched everywhere for frame dimensions for a 4 wheel drive frame.
I need to know where to put the leaf spring mounts.
There just does not seem to be a drawing that will show the placement of the perches.
The 71 c20 long bed frame I have has leaf springs at the rear. The mounts are 52" apart. Or is the k10 spring shorter?
I need to drill and mount the rear spring perches for the front axle as well.
Anybody got a length from the core support mounts to the rear? What spring length?
Small images of frame dimensions suck. The print is too small to read and if you blow the image up, you still can't read them.
Please help.

[Steeveedee]

Go here and download the service manual with 133 in the title for your year truck. Frame info is in section 2. It has dimensions, but you may have to print the pages and use a scale for precise locations.

https://67-72chevytrucks.com/vboard/...ghlight=hatzie