..but rancho's spring rates for the 2 1/2" front is 390 in/lbs, the Mohave was 195~225, depending if you used the option "2F" leaf.
195 was for the V-8s. Rancho's rears are 290, Mohave was 175 ~ 215 , optional leaf for those with hardtops, aux tanks, roof racks
and tire carriers. The rear was a 6 leaf pack , the front was seven leaves. Thin leaves with a lot of free arch. The rears had 11" of free arch.
There were 4" long 16 gauge spacers between the leaves at the center pin combined with the teflon buttons at the ends of each leaf.
This left a gap between leaves eliminating most of the friction between the leaves. Less friction means faster cycle times and a faster response to bumps. With 11" of free arch and that spring rate a typical 40 would squat to a 4" lift. It required 2.5"~3" over shackles as the springs were about 3" longer than stock, 2~2 1/2 longer than most 2.5" lift springs. It allowed 10" vertical travel measured at the shock . You could drive up on a 33" tire and the other three would stay planted.
It did, however, require changes in the front. A shackle reversal, 80 series front driveshaft slip and yokes and taller shock towers to get the most. The stock towers weren't tall enough for a 10" travel shock. Stock 40 or 60 series ujoints wouldn't handle the angles at droop. The 40 and 60 have 24~27 degrees of articulation vs 45 degrees on the 80 front. The 80 rear uses the same low angle joints as the 40 and 60. The 80 slip yoke has almost 3 times the spline length as the 40 and double the 60 for the extended travel .
The complexity probably swayed some away from the system. There is no simple long travel, Cadillac riding bolt on answer. Short leaves are hard
to get a great ride out of. If you've ever ridden in a CJ5 or a mid 60's Scout you'll understand