Transient Voltage Suppressor

[JamesC]

I was planning to replace my starter and battery solenoids (it's time) and looking up the part numbers, and noticed part number C591501-0101 - Transient Voltage Suppressor - it is -57 on Figure 138 (Electrical Equipment). Does anyone know where this is (eg. is it even forward or aft of the firewall - difficult to tell from the diagram) or had trouble with it or had to replace it ?