Will these S4 parts work on a S5 to the same efficacy as stock S5?

-Wiper switch cluster
-Fuel level sender/assm
-Diagonal seatbelt (will S4 seatbelt mount acceptably in a S5 w/ tracks removed?)
-Alternator
-Door/shock tower speakers

 

-Wiper switch will fit but the wiring will have to be adjusted (depinned at connector)

-Yes

-Yes, with a caveat.
The seatbelt reels, etc. are a bolt in but the trim panels will need a bit of adjusting.
The lower B-pillar panel requires a little trimming to allow the belt to escape from behind (be very careful here, it really doesn't need much). The upper B-pillar will need a hole drilled to allow the upper belt pivot to screw in. The A-pillar trim will lose all it's mount points but will basically sit in place fine.

-Yes but it's a downgrade (lower output)

-Rear speakers yes, not sure about the door units

 

Connector will connect, but pins switched around?

 

pretty sure fuel level/sender assemblies are different. gas tanks are different capacity. i went from s4-s5 a few years back and i feel like it was one of the things i thought wouldnt have been an issue.

 

*Also: different connectors on the alternators..

 

everything you listed is compatible with minor adjustments. the alternator for example will have to have the s4 connector wired into the s5 harness. i dont see why you would want to do so though. the s5 alternator pushes better than that of the s4 but it is workable. and for the seatbelts, i went the easy way and just bought 4 point harnesses and mounted them to the floor bolts and to the back of the frame where the hatch latches are. easy and very sturdy.

 

fuel level sender is the same on all fc's. its just the size of the tank that is different bud.

 

Came back from the junkyard. Ended up grabbing not only the wiper combo, but the headlight combo and the turn signal combo switches.

So, the S4 wiper combo has the same connector and mounts as S5, but the pins pattern is different?
What about the other two, similar case for those? The switches look in good shape aside from age grime (good contacts, the harness was clean, the exposed electronica is clean)