Up for your consideration is a Replacement RAYMARINE BELT D169 for AUTOHELM RAYTHEON AUTOPILOTBELT ST4000 AutoPilot Wheel Pilot
MK1 = Old version Black housing.
The Mk I version has a black wheel drive ring.
Therefore it fits units with BLACK housing cover only.
This belt has 150 teeth. Marked T5-750

This belt will Not fit 4000 Autopilots MK II ( MK2) with GRAY cover!