There is no need for the heavy, ugly Ferd relay/solenoid. You can buy a 60 amp 4 pin relay that is only slightly larger than the common 30 amp Bosch relay. Since the relay is switching solenoid current only which is under 60 amps [ 35-50 amps usual range] , this relay does the job.
My understanding is that the big Ferd sol was used on their Integral Positive Engagement starters. These did NOT have a sol mounted on the starter, so the separately mounted solenoid switched several hundred amps of current to the starter itself.
