Nothing standard-issue. I tried Mcmaster and a few other sites as well as my local HW store. The springs are about 1/4 diameter with open hook ends.
I did find some older ones in a stash box that are usable, but I am working on finding a real replacement that won't require buying a whole new arm.
1966 109 5 door wagon 300Tdi "spermaceti fueled"
1994 RRC LeWiB "ruining the air behind me"
All my troubles are Rover