1988 chevy silverado stalls dies...crankshaft position sensor?

Hi there. Okay so my sons truck has been stalling (mainly on left turns) and dieing and we have replaced numerous things (fuel pump, etc.) in all my googling people say they had the same issues and replaced the crankshaft position sensor and it solved the problem BUT..in the repair manuel it says only Chevy trucks years 1996-2000 have this CKP sensor "thing" soooo...what does it use instead? W/e it has instead of this sensor is something we'd like to look into replacing. Car has been in the shop 2 times now and they cant find the problem. The sensor replacement seems to be the most successful repair in stories I have read online. Thanks.