The Cologne V4 and V6 engines came with a camshaft gear with a neoprene/plastic fiber, something like that, pressed on it that would disintegrate at around 50k-60k miles. They were a metric cut. In North America the replacement was SAE, which required more work to replace the gear on the crankshaft. In Europe you could get away with just replacing the camshaft gear. I guess the advantage was that the engine didn't have to be pulled. The disadvantage is it usually failed without warning which left people stranded. I flipped a few cars in the late 80s that I bought cheap because they wouldn't run. A Saab Sonnet with a V4, several 2.6L Capris, and a Bobcat and another Capri with a 2.8L.
There's some history here. The Cologne V6 was designed after a V4 that was cast at the same Ford plant. It had interchangeable parts with the 1.8L-2.6L Cologne V6 engines. I replaced a cracked timing cover on a 2.6 with one I got off of a V4. It got cracked because I set up the 2.6 on a bench and started it without fastening it. My idiot friend walk up to it and opened the throttle and the torque spun it off the bench and on to the floor. The timing cover, one valve cover were the only things that were damaged along with a chip out of the garage floor. So, the lesson here is don't do what I did if you are surrounded by idiots in the garage.
en.wikipedia.org