I have a bone stock 1990 mustang that I have had for over 20 years. It runs great other than I have some oil leaks that are hard to diagnose. Due to he limites space and my desire for a clean shop floor, I am planning on pulling the engine and transmission, and replacing every gasket including the head gasket. I also plan on having a valve job and new seals put in the heads. (60 bucks at local machine shop).

Since I would have everything apart, I thought about replacing the oil pump and timing chain while I am at it. This got me to wondering about aftermarket parts. For the most part, on my other vehicles when I have gotton a part at my local autozone, I have had mostly good luck. However there have been a few exceptions. For one, a borge warner distributor cap/rotor replacement on a 96 Silverado. About 8 months after a replacement, I developed a miss. I ended up replacing just about everything but the cap trying to find the cause. (I figured the cap was new so it could not possible be the cap!)

So, what I am getting at is, if I were to purchase a Ford Racing oil pump for 20 bucks online, can I expect the same amount of life as the one that came in my car in 1990 and now has over 100,000 miles on it? What about a ford racing timing chain?

At one time I went through a spell of ordering what I thought were "factory parts" online because they said "motorcraft" on it. But if you read the fine print on some of them, it says that basically the part may be subbed out to a third party. So, if I buy a motorcraft part online somewhere, is it the same part I would get if I were to go to the to dealer an order a service part or not?

Not to change the subject, but is there anything else you would do while you had the engine out of the car that is not too expensive? I plan on re doing the heads as I said, new gaskets, timing chain/sprocket, oil pump, clean the oil pan and everything up. (Even wondered if it would be hard/worth wild to replace freeze plugs. (But it gets to the point where you are almost rebuilding the whole motor....)

Thanks!