I have a 96 454 330 hp will the Thunderbolt V distributor fit in a new GM 502 marine long block? I used the stock 454 dual plane manifold. When I Install the Distributor in the engine, the distributor won’t sit flush in intake manifold. It sits about 1/4” off the manifold and that is with the gasket on it. Am I missing something?/

They use same distributor. You are probably not seated into the oil pump drive, which is just a slot in a shaft that mates with slot indide distributor gear. Turn dist upside down, look in gear, - see it ? Using a long bladed flat blade screwdriver, turn shaft just a c hair (that’s a measurement ) counterclockwise. Try dropping dist in again.

I f i didn’t make sense, search u tube for vids on installing distributor n small or big block chevy.

Thanks for the help, that was it. Really appreciate the reply

You may want to make sure you are using the right gear for your cam

was it a standard or red c hair? A bit of a difference...