Which coolant temp sensor for 2.5? Dual?

[ianbword]

I noticed there was two different coolant temp sensors for my 86 120 hp 2.5 lt. What do they mean when they say "Dual" did people run 2 sensors on a 4 cylinder?

5	806490T	SENDER ASSEMBLY, Water Temperature	97257A1	SS/ACT		$30.83	$30.28	1
5	49734	SENDER ASSEMBLY, Water Temperature (DUAL)	49734A1	SS/ACT		$69.50	$65.45	OPT

http://www.mercruiserparts.com/bam/subassembly/30885/963/80


Thanks

 

[Bt Doctur]

"Dual" meaning 2 helm stations using