I did a 6" rear drop with c-notch recently and decided I'm done pulling the middle leaf on 5 lug packs. Even just temporarily while the person looks for 6 lug leafs to pull a leaf from.
Mono leafing is out for me. The main leaf wasn't designed to bend the wrong way so much. Laying flat across the overload and then dropping off, creating a shear point. It was designed to curve like a smile with leafs beneath it helping it out and achieving a progressive spring pack. Even with just one leaf under it. (like stock)
Specimen: A 98 extra cab that's going to haul 2 street bikes with air assist. So this means there isn't even a need for overload leafs on this truck.
Originally, I was going to just do what's been the norm and pull a leaf from his 5 lug packs, and use 3" blocks and overload leafs until he could locate 6 lug leafs. I never felt good about just having one main leaf do all the work, especially with 2 heavy street bikes, even if there were going to be air shocks and air management system.
This truck came to me with a 2" lift all around. Somebody had removed the stock overloads and replaced them with short little stiff curvy AAL's. The front had a set of horrible Fabtech coils that should never be installed in a 5 lug imo. Better suited for a dodge ram. Not feeling good about it, I pulled the middle leafs, installed the 3" blocks, and used a set of 4x4 overloads I had here. I cut 5" off each end of the curvy 4x4 overload leaf, making it more like a 5 lug leaf. However, 4x4 overloads curve more than 5 lug overloads, so what I ended up with was a truck that was obviously going to be way too low in back. The axle came right up and contacted the frame when I knew there should be at least 1" to 1-1/2" between the axle & frame for a 6" drop. I also noticed how weak the main leaf is when is has no help, and it was bent the wrong way so much I felt sorry for it.
So I tried a different setup. I put the 5 lug leaf that I had removed back in, but eliminated the 4x4 overload, and kept the 3" blocks. This combo sat too high in back. So I made a set of 4-1/2" blocks and took everything apart and back together for a 3rd freakin' time.
This was the combo I finally settled with. Stock 5 lug packs with both leafs but no overload and 4-1/2" blocks. The leafs are almost flat, with a slightly positive arc (curve). They remind me of the old Chassistech leafs.
In my opinion, this is a better way to go compared to running just one leaf bent the wrong way over the overload spring. Some people may not be too fond of the block height with this setup, and will still prefer to locate a set of 6 lug leafs and use the 3" block to achieve the 6" rear drop, but I do like the fact you can get away with the low drop, still have 2 leafs and not have to locate a set of 4x4/prerunner leaf springs.