I've been doing a some P/M on my 69 Road Runner survivor over the winter & while the radiator was out, I figured that I'd pull the water pump, balancer & timing cover off to replace the factory timing gears and chain. Of concern to me was the plastic coated camshaft gear. In spite of the car's low mileage (33,000 mils), I'm sure that plastic wasn't meant to last 52 years. No teeth were broken, which was a relief, but when I pried the crank gear off, I noticed that there was a strong 1/16" - 3/32' play in the crank, front to rear which isn't good. The next step was to pull the oil pan and #3 main bearing. Once I did that, this is what I found.... Front face of the thrust of bearing... Rear face of the thrust bearing... The actual bearing journal surface of the crank & bearing are fine with no scratches or debris imbedded in the bearing. I started thinking about what could have caused this & the only thing that I can come up with is the previous owner cranking a cold engine that sits for long periods of time while pushing the clutch in. With the clutch pedal is depressed, it pushes the crankshaft forward which in turn puts pressure on the rear of the thrust bearing & if it's dry (from sitting), this could be the end result. Seems to make sense to me, but if anyone else has another theory, please chime in. When I bought this car, I also bought a bunch of NOS parts & included were new main & rod bearings, so I put a complete new thrust bearing in which tightened the clearances up. There was a slight amount of wear on the side journal which made the end play slightly over spec, but I'm sure that it'll be fine. I'll be buttoning things up as soon as my cam gear set comes in & will report on things once I restart the engine. We all know that it takes some cranking to get the gas up to the carb when th car has been sitting for a while & my advice now is to always start a cold 4 speed equipped car without depressing the clutch.