that option was found on b0th the 235 & 283, the same parts I think, and the details are in the shop manuals from 55.2 onward .... it appears Keiths site is currently being moved to a new place and is unavailable
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics