You need an 80-81 Getrag 5 speed to get a speedometer drive. These came in a variety of models. You might be able to find a 635 or 735 from those years. Alternatively, this same transmission was used in 82 & 85 528e's and 85 535,635 and 735's, as well as E30 M3's but without the speedometer drive installed. You could have the drive gear and drive from your coupe installed (they are the same parts-I've done this). Note that if you get the 528e transmission, the bellhousing won't fit your engine, but you can use your 4 speed bellhousing.