660 and 700 suspension?????

Im trying to figure out whats the difference in the two suspensions, axles, diffs, etc.....

I did a little research and figured out that the rear a arms are different part numbers but why?  I know the axles are not interchangeable but why?  Bearings are the same cause I used 660 wheel bearings before.... Im stumped on this one....

Reason being, I can find a bunch of mid travel kits for a 660's just not a lot for 700's ...  found a new set of a arms for $500 but they for a 660....  little help please

as far as I know the difference is the axles, the 700 is longer in the rear, but I think thats it! oh and you need longer brake lines for the 700

So if I use the rear 660 a arms, I'll need 660 axles correct??

nope you can use 660 a arms or vise versa it the axle that you need specific to your year

Got my wheels turning again!!!
Thanks for the help!!