The factory spec for the front wheel caster is 3 degrees. The 4″ of lift at the rear of the 83″ wheelbase will give -2.76 degrees, so I’ll end up with almost no caster.
Here’s a source for custom shims: http://www.4crawler.com/4×4/ForSale/Shims.shtml#CustomWidthShim
Because the 4″ rear lift springs will adversely affect the rear drive shaft angle and the carb level, I want to lower the transmission/transfer case crossmember to compensate. The engine mounts and crossmember are 28″ apart.
To get the percentage of the drop divide the engine mount to crossmember distance by the wheelbase.
To get the spacers needed multiply the % of drop by the 4″ of lift.
0.337 x 4 = 1.348
So we’ll need some 1.348″ spacers to lower the crossmember.
carb parts http://www.vintagespeed.com/
Britool Hallmark 3/8″ drive Fine Tooth Ratchet MR200FT