I won't argue the point, I have references that call them slotted Fowlers. They do move rearward as they drop down. The Bird Dog wing is the same as the 170 wing, basically the A model L-19 is a tandem-seat C170 with more glass and some redesign for the narrower cockpit and windows. I suppose it may have been a specific criteria for the military to have flaps that extended further for short field operations. Later variants got a bigger engine and constant-speed prop but the airframe stayed the same. Gross weight did increase and affected flight performance a little, such as an increase in stall speed.