The door mirrors were revised for the mk4 version and made more rounded without the option of having body colour coded inserts. They were available in much the same flavours as the mk3 versions, i.e. manual adjustment, internal mechanical adjustment and full electric adjustment. On vehicles fitted with heated front screens the mirrors were also heated operating from the same switch.
The only benefit of fitting the mk4 door mirrors to your mk3 Escort other than cosmetic if you happen to prefer them is that you are more likely to find a pair of electric mk4 door mirrors than the equivalent mk3 item (most mk4 shaped Orion Ghia's had them fitted).
Don't forget you will also need the looms for them. This includes the door feeder looms if you don't already have them and the loom from behind the dashboard.
Fitting
Sadly fitting the mk4 door mirrors isn't the straight bolt on job you'd expect it to be. Both mirrors are held in place with three bolts but Ford in there infinite wisdom decided it would be best to move the positions of these bolts on the mk4 version.
However, to make the job easier Ford do provide a drilling template with them. On removing the mk4 spec mirror from it's donor you will find a rubber pad sandwiched between the mirror and the door. Use this to mark the positions of the new holes on your mk3 door. Note that the holes on the outer skin need to be just large enough to allow the mounting legs to pass through but the holes on the inner skin must only be large enough for the shank of the mounting bolts to pass through.
Needless to say, getting the electric versions to work will depend on what wiring loom you are using.
The contents of this website are purely a reflection of my own experiences and knowledge gained whilst working on my various projects. Anything you do based on what you have read here is done so entirely at your own risk. Personally I wouldn't trust someone like me with a lawn mower! You have been warned! Flapper-bat!