This is an LT1 engine and is a reverse flow engine design. The OptiSpark is the distributor and is on the front of the engine. You have to remove the water pump & the air pump to get to the OptiSpark. The O/S distributor is expensive. I would try replacing the plugs with the rec. AC Delco plugs. If that doesn't cure the miss, try replacing the wires. I want to warn you this is a major job. You can't get at them from the top, so you jack the car up and try to get to them from the bottom. It is a frustrating experience because they are routed under the cyl. heads and just over the cross member. I had to get an experienced LT1 mechanic with a lift to replace the wires on my 1994 Impala. Oh, yes, if you do replace the Opti, consider replacing the water pump, too, if it hasn't been replaced lately.