I dont know about 3rd gens. both of my Escorts are 2nd gen. Neither has an armrest. Im thinking of making one up, using a couple of pieces of 1/4" or thinner plywood for the sides, with a wooden board for the top, having foam padding and a scrap of fabric over that - stapled to the board. It would need careful shaping of the plywood supports so I could still work the handbrake. I think I would make it about half an inch higher than the driver's door armrest.
I did this same kind of thing on my Dodge Omni years ago, and found it very comfy on day-long drives when on business trips around the Eastern states. It wasnt attached to the car, but just sat in place, slightly wedged between the seats and the shifter 'hump'. It could be tipped back if it was in the way (when I dropped anything down beside the seat).