All A500's were lock-up, some A518s were not. The overdrives got better, but Mopar cheaped out on some parts. The servo and accumulator pistons were plastic, which were prone to warping/leaking with age. Superior makes nice billet aluminum replacements for reasonable money (or use earlier factory metal parts). Most 500s were behind 3.9 V6s, so the typical 904 beef up guidelines apply like the front drum.