Topic: 1965 change-over from 2 to 3 speed heaters

[midlife]

Just curious when the 65 model year (not 64.5) changed from 2 to 3 speed heaters.  Why?  There are two different underdash harness configurations, and am just curious as to the date or VIN change-over.  I have customers wanting an underdash harness for their shell and I have to ask a whole lot of questions about heater blower wires and switch designs to figure out what the correct harness is.

[markb0729]

If this helps I have a 65 Dearborn built Fastback.  Approximate build date is September 2, 1964.  It has lots of early 65 (64 1/2) parts including the heater.  The heater motor is 2 speed, 3 wires, no resistor in heater box.  Switch is center off with low speed to the right and high speed to the left.

[CharlesTurner]

The MPC date is 4/1/65.