Does anyone know of a source for the rear shock rubber bump stops (#6 in the diagram, part number 914-333-053-01? The only suppliers that had the stops listed, Stoddard, told me they can no longer get these. AA lists them, but with Stoddard as supplier.

Has anyone tried the "generic" Bilstein stops? Or other stops?

And how necessary are the stops on a mostly stock 4 cylinder car with 100 lb springs?

If you are using Bilsteins they are not necessary in my opinion. Gas shocks won't compress that far. USE the washer that is part of the base in the stack though. Several suppliers do have Koni hard rubber stops that can be used.

I think Bilstein says to leave them out.

I installed the ground control coilover system with Bilsteins and they recommended cutting that rubber stop at one of the indentation lines. I don't recall which one, but there was a diagram in the instructions.