I goes where the distributor goes in a normally aspirated engine, of course. Chances are either:
- The gear is worn (slim chance)
- Your timing chain is going (better chance)
- Your sensor reluctor ring is damaged (high chance)
This may be all it needs:
http://www.rjcracing.com/RJC_Buick_P...camsensor.html
Hard to tell without being there. Pull the two screws on the top of the cap and see if there is any play in it.