Water pump differences? 68, 69, 70...??

69 and earlier used the cast iron pump with the driver's side exit. 70-up used the aluminum pump with the passenger side exit. Earlier timing chain covers varied as some used a bolt on timing chain marker and other the timing marks were built in. I think that cutoff (more or less was about 67/68. I think 70 up timing chain covers were all pretty much the same.