Congrats on your new purchase. I recently pulled the instrument
cluster on my '84 P'up to replace some lights. It's not hard at all.
I agree with BuddyWh, it may not be the speedometer. Does your
odometer work? (In not, it's more likely the cable, not the
I don't know what the speed sensor is, but I suspect it's part of the
speedometer assembly inside the cluster. This is an all-mechanical
unit, unlike newer vehicles. I have the factory shop manual for my
'83, and I'll look this up for you when I'm at home.
Or, you may want to post your questions over at the IsuzuPup.com forum
(http://www.isuzupup.com/forum ). I run this site for owners of Isuzu
Pickups, primarily the '81-'87 models. We have a very active forum.