Flywheel dilemma

[cigar-]

I have a 1971 half ton truck I am working on. It came originally with a 250 cubic inch inline six. Somewhere prior to me the six got pulled and an 350 got dropped in. The truck originally had a three speed column shift. When I got it it's now a floor shift.

I have the new motor ready and about to go in. I'm thinking of putting on a new flywheel as the one off the old motor has some bad teeth. What I dont know is if the flywheel I have is off of the inline six or not. It's a GM part with the number " N 6668868" on it. I searched the net and found nothing. It measures about 14 1/8" across the teeth.

Napa Auto Parts sold me new one that wouldn't go onto the back of the crankshaft. It seems the hole in the Napa (Chinese) flywheel is .010" smaller than the crankshaft journal where the flywheel mounts. The one I was sold was supposed to bigger in diameter than the one I pulled off. Something about a bigger clutch means better grabbing.

Has anyone ever run into this situation? I simply want to get the truck running. I am not worried about pulling anything heavy as its going to be a beater truck.....maybe pull a small trailer someday.

Please.....anyone.....help!!!!!!

Michael