I would get the "new" ones on as is, and test them out. Find some place/route/path you can take again with the mods to really feel the difference, best direct comparison. Might even want to take some body measurements to see the diff.

SDTruckSprings.com shows measurements for stock replacements, if that helps. Also puts a new pair around $300, making me like this idea more and more. When I get to this project, I would definitely try to get that top one doubled up, any addition to the bottom or middle still has the weight run through one leaf at the top mounting. I'm NOT saying thats right or best, just what I would do, having a similar situation.

 

ok guys so today i did the leaf spring swap....all in all not that bad.
took 6 hours...the bolts on the front end bushings of the leafs did not want to come out...but they did.

so here is my "bastard" pack.
i cut the eyelets off the old main springs and slipped them into the "new" pack.


like so.....^^^^

then i installed them...well lets say with my "new" and the old main added i had gained some lift.
i am not sure how much this is related to my old one being whipped or not.
but luckily i have the autozone shackles doubled up on each side so i was able to adjust the rear back down....i know i know...i wasted perfectly good lift inche or so.



so with the final adjustments and a good road test both sides settled out to a nice 44 1/2" from ground to top lip of wheel well....which is about 1/2" higher than it was...so not bad.

now for ride quality.
i noticed several things right away.
my wheel hop that i had from dead stop is now gone.
body roll is reduced
ride is stiffer but not bad...i like it.

so for the 90.00 and change it cost i like what i got in return.
z85 springs 90.00
hardware 5.00

and i am a happy camper.

 

Now that's better.

 

Dude amazing... good freakin deal

 

thats pretty much what i did with mine, passenger side was broken at the shackle so I got a set from the yard for $100 and popped new bushings in them and used the old top leafs as AALs, raised my truck almost 1" in the rear. I need a t-bar crank to even it out, but don't want to get an alignment done yet

 

My leafs are sagging aswell (same one you had). I found 2 brand new main leaf springs locally for $50, he says he paid 200 for 'em. think I will look into it!

-OSS