I'll try to post the article from Super Stock & Drag Illustrated,
Bill 'Grumpy' Jenkins, when he was running the 65' Plymouth Race Hemi 'Black Arrow' had a great article on Rear Suspension with the Mopar Leaf-Springs.
Distance, Height and Shim-spacing.
He revealed every little trick he had, before moving over to Chevrolet at the end end of 1965.