Used to have two "F,s"; came with 13' "feeler bar headers"; this was in the early '70s.They worked all right, but didn't cut very close to the ground. Swapped for two 16' floating cutter bar headers. Just hooked up and drov'em off. No modifications required that I remember. One was Series One and other was Series Two. They worked great, but gave the F's about all they could handle.
