FORD 2013 F-550 v.1 - Manual (Page 158)

Recline Adjustment
Manual Lumbar (If Equipped)
The lumbar support control is
located on the outboard side of the
seat. Turn the control to adjust your
support.
Seats 157
2013 F-250/350/450/550 (f23)
Owners Guide gf, 1st Printing
USA (fus)