Here's some information that's been discussed and verified a bazillion times on Moparts.com. Since I was new to A-bodys, I researched it myself by looking at about 45 Plymouth and Dodge A-bodys in junkyards (both V8 & six) and cross-referencing many part numbers from factory parts catalogs.
73-76 center links are all the same regardless of engine. They appear to be very straight across. The pitman/idler arms enter from the top. I've personally compared the center links from many cars with both V8 and /6 and they are the exact same unit. Also, my '76 parts catalog only shows one number for all engines.
70-72 center links are all the same regardless of engine. The pitman/idler arms enter from the bottom. The links appears to have about a 1" drop. I've personally compared the center links from both V8 and /6 cars and they are the exact same unit.
I cannot comment on anything earlier than 1970, because I've not personally seen any.
You cannot properly install a 70-72 link onto 73-76 pitman/idler arms because the taper in the link's holes and the taper on the arm's studs will be opposite each other. This also applies to installing a 73-76 link onto 70-72 idler/pitman arms. You can't mix & match parts.
It's also my understanding though owners of earlier cars that the only A-bodys that have a V8 center link and a /6 center link are very early cars (64-65, I think). I've never really seen anything older than 1970, so I cannot verifiy that.
I've personally crawled under way too many 70+ cars to disbelieve anything I've cited above.
Word to the wise: Don't buy anything labled as a "V8 center link" unless you have a very early 60's A-body. Why? There's no such thing - they all work with a V8 as long as they are used with the corresponding generation's suspension components.
