My '85 only had the square plastic pre-filter, but I added the after-fuel
pump metal filter later.  I think the pre-filter is especially important if
you are still sporting the original gas tank.  An '85 gas tank probably has
a lot of junk floating around it.  To check, cut open that little white
plastic filter the next time you change it.  Mine was full of rusty crap.
 Now have a new gas tank.
Maggie
'85 Subie-Westy "A.B."