Torque Converters for Internally Balanced vs Externally Balanced Small Blocks

First, a question. How do you know the engine isn't "highly out of balance" if you didn't have the machine shop balance it? If it was out of balance before, guess what? It still is.

Ok onto your question. Yes! The 360 requires an externally balanced converter with weights on it, AS WELL AS an externally balance harmonic balancer with either an offset weight on it, or a large "groove" cut out of it. There are two types and I believe they are interchangeable. Although, all that said, skipping having a new build balanced is a mistake. I think you found that out.

Now, there is something different you can do with the converter. You CAN run a neutral balance converter if you use the externally balanced flex plate B&M makes that has a "bite" out of it to balance the 360. So that's another option there. But you need to inspect the converter for weights. They will be welded to the front of the converter, just behind the dust cover, if you have one. Also inspect the balancer to see if it is externally balanced. Feel free to post pictures of both and we can help determine what you have. Lastly, I would VERIFY that you do indeed HAVE a 360. A lot of people have gone through this only to discover they have a 318 or some other small block.