The late 85 uses the early sway bar with the late cast iorn suspension.
Looks like only inner and outter bushings need changing along with the new
sway bar.The straight end links are used with the early bar in this 85.

I dont see why you cant use the late bar in the early sheet metal lower
control arm suspension. Use the dog leg or straight end links.The thinner
bar will cause less stress on these links.I think the larger bar, caused
the cast iorn dog leg end link, to snap at the threaded part.This, when
wear occured in a worn suspension. I guess that is why VW changed to steel.

 My early 85 came without an end link on one side. Probably like that for
years.I saw several just like it in the junk yard.Why do you want the
thinner bar?