After a perusal of the old chevy manual in the 1950 front suspension section shows the mounting shackle at the spring front mount. My truck has the shackle at the rear. This would certainly affect the geometry.

So what is correct for my 49 GMC 2 ton FF 353 coe truck?

I know I`m not the first owner to have the front end apart and maybe the previous owner had accidently it mounted backwards?