dakota Transmission
Both tranmission will bolt up to the 360. the A500 is basically a 904 and the A518 is basically a 727. I picked up an A500 in an '87 Dodge Van and an A518 in a '92 Dodge Van. The A500 was behind a 318 and the A518 was behind a 360. So if you want an A518 you have to look in trucks. All of the A500's had lock-up convertors but the A518 for the most part had standard convertors until about '93-'94. The easiest way to tell is the non-lockups will have a 2 wire connector and the lockups will have a 3 wire connector.
Chuck