quick question about s4 upgrades
 

i have an 86 na and a 90 gxl i'd like to know if the wiring harness is set up for the plug in for the rear windsheild wiper and the power windows , if it's just a matter of bolting them on and pluging them in . please let me know

If they both have a rear windshield option then just check out the plug ends and see if the patterns match. If one does not have it, check to see if the wiring is there in the rear hatch. If it's not there then it's custom time. :)