360 Internal or External Balance??

ALL 360S WERE EXTERNAL BALLANCED.340s made in 1973 and newer are cast cranks,and EXTERNAL BALLNACED.318s went to cast cranks in 1970 or 71.That is debateable,because ive got 2 71 318s that came out of one owner cars and there both forged cranks.Now 318s in straight drive applications remained forged for a few years,im not sure when that stopped,but i have a book that tells for sure somewere.The book "How to hotrod smallblock Mopars"Is a good place to find specific years and casting numbers for cranks that your not sure if its cast or forged.Also,all 273s had forged cranks.As most of you know,but some may not,you can put the forged crank from a 273 right in any 318(premagnum)or 340 if you currently have a cast crank engine.Then you can run the thinner,lighter internal ballance harmonic ballancer.Now knowing that 273,318,and 340 all had pistons that weigh different,its hard to believe they are ballanced correctly from the factory,but thats how production stuff goes i guess.As a side note,All 383 bigblocks had forged cranks,and they are the same stroke as 400 b blocks,so they are a direct replacement for the stock cast crank 400s.