I feel like an idiot...

Well, I've been chasing a vibration on my 74 Dart Sport with a 318/904 for a while now. Changed rims and tires, tailshaft bushing, transmission mount, u-joints, pinion angle, etc. No improvement. Wanted to rule out the driveshaft being bent/out of balance, so ordered a brand new one. No improvement.

Had a look at the harmonic balancer, thinking a previous owner might have put a 360 balancer on there. It didn't have any weights on it but looked to be wobbling, so I ordered a new one from Summit.

My starter was making a noise like the bendix was sticking, so I crawled under to have a look. While under there I decided to check the flex plate to torque converter bolts, and I noticed the torque converter had weights on it. Maybe that was the vibration, the wrong torque converter.

While I was down there I decided to look at the block and get the casting number, and what do you know, it's a 360. :banghead: The casting number is 4006830-360-6. So the torque converter is right, but looks like the balancer has lost a weight and may be worn out.

Called customer support with Summit and explained to the guy I had ordered the wrong harmonic balancer, and he said the one I ordered for the 318 would work on the 360. Well I may not know how to tell a 360 from a 318 by looking at it but I knew the one I ordered wouldn't work. Even after telling him their website had one balancer listed for 273/318/340 and a different one listed for a 360 he still said it should work. We ended our conversation with him telling me if it didn't work just return it. I then called back and spoke with someone else and got the 360 balancer on its way.

So all this time I thought I had a 318 and its really a 360, I've been buying parts at the parts store for a 318. Luckily everything I've gotten works on both. I was just going by what my brother in law and his dad told me when I purchased the car from him, and they are life long mopar guys so I figured if they said it was a 318 then it had to be so. On the bright side I have a set of headers that I was waiting to put in when I could get a 360 built for it, looks like I can go ahead and put them on....