I can't answer that. I don't know why my GMC Suburban with a 6.2L diesel came with a single pulley alternator set up either. I have found only one belt that will work on it and it has to be tight. It will last about a year. Once it starts to squeal it will never stop. Go figure.

TimK

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EPA 609 & 608 HVAC Certified
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83' 300D Turbo - 300K + Miles
00' 1.9L TDI Beetle
85' 6.5L Turbo, GV-OD, GMC Suburban,
67' 2.5L Diesel NA - Land Rover Series IIA

Here's what you do if it's so cold your diesel fuel gels. Smear some on some toast and stay inside until it warms up outside.