[Richard]

Most of the dual shock lower mounts just use the stock dual shear lower tabs with a longer bolt and a spacer between the shocks. Adding another tab to the axle on the outside of the addon shock will put both shocks in a double shear mount and make it stronger. Look at places like RuffStuff for mounting tabs to modify.

Edit: No doubt a nice single King or Fox reservoir shock could be better. May require some tuning to get it where you want though. Bummer your post got moved into this place. Re-reading the original post I can see no fishing for people to sell you parts.