The U.S. aircraft register, updated daily
Parts

Seatbox

No failure report names the seatbox. 1 FAA approvals let 1 company make a replacement seatbox, Dakota Cub Aircraft holding the most (1).

Approved replacement parts 1 parts manufacturer approvals

A parts manufacturer approval (PMA) lets a company other than the aircraft's maker make a seatbox and sell it as an approved part for the models named. These are the companies holding such approvals for a seatbox:

For these models most: Piper PA-18 Super Cub (1).

MakerPartReplacesFitsGrantedStatus
Dakota Cub AircraftSeatbox Assembly - Rear Seat S18-1100-ASSYModification PartPiper PA-18, PA-18S, PA-18105 Special2010-03-18current

Sources: the FAA's service difficulty reports since 1995 (a report is a part that failed and was fixed, as filed by an airline, repair station or owner; the count shows reporting as much as reliability) and the parts manufacturer approvals in the FAA's Dynamic Regulatory System. The part name is the reporters' and the approval holders' own words, reduced to the first plain words so that spellings meet.