where can i buy individual leafs?
Go to your local boneyard, pull 'em yourself. The one by me is cheap as hell, would only have been about $25 for each 4-leaf pack. I did the same thing on my old Suburban, dissambled the rear pack before I took it to the junkyard, and used the leaves in my Tahoe.
In the 'Burb, I slipped 5 extra leaves in the pack.... it brought the ass end up a good 6-7", had to use u-bolts to clamp the leaves together to bring it DOWN....
Oh, and Bowtie.... the 1/2" bolt replaces the stock 7/16" one that bolts the leafs together, I rounded the head over on a grinder so it would fit in the hole on the axle pad. The u-bolts I used were new 5/8" diameter, just like you did.