Also on page 172 of MAC's catalog, you can buy just the springs. The one you need is at the right end of the illustration. Part # A46125 , $4.85 for the set.
The part number you named is for springs, rods and brackets.
We sell that spring by itself for $.50 (part # A47124). We will ship it US mail for $1 with no service charges. Just a thought... Berts Model A Center Denver, CO www.modelastore.com 303-293-FORD