I believe they're only on OBD II motors and it attaches to the front of the oil pump behind the crank pulley and reads a gear wheel attached to the end of the crank. If you pull the crank pulley off and remove the lower timing cover, you can't miss it (although I doubt a B18A will have one).
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Andy - Reinstated
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'06 Subaru Legacy Spec B - Stock, for now
'98 Civic EX - CTR headlights and grill, Kosei K1's, for sale
'90 240SX - SR20DET that will never get installed, project car.