Any Aisin pump is OEM Toyota. (That is who Toyota bought them from.) Same as our Transmissions, they are from Aisin as well.
You guys realize that 80% or more of the car is NOT built by Toyota right? (This goes for every car maker, the average is actually 18% is OEM.)
The CRITICAL difference in the pumps is are you getting a 7MGE or the 7MGTE pump. I would always buy the turbo engine pump. (7MGTE pump.) The housing is the same in every way, except the turbo pump has a taller gear set, so you get more flow. Either fits in either motor, but there is no down side to more flow.
When you get your pump, take the top cover off. (There are a few small bolts holding in on. They are quite tight, so be careful both removing them, and when you re-install them.
Every new pump I've taken apart has some small amount of gunk and debris inside. You do not want that in your bearings right? Clean it.
Now, you do want some lube in there, so I like to pack my pump with assembly lube, then put the top cover back on. While you have the top plate off, or when you have it back on, you want to remove the pressure bypass nut. Be careful, it's holding a spring under pressure, so it will fly off! Now, you have to make a choice, to shim, or not to shim. Non shimmed motors have run many 100's of thousands of miles, but extra oil pressure is not a bad idea, so I like shimming. I've found one 10mm nut does the trick. Or 2 or 3 flat washers. Now comes the tricky part. You put the bypass valve in, then the nut or washers, and then the spring. and then find the retainer nut is VERY hard to get started. I found a short socket wrench allows you to push it in, compress the spring, and still turn it to catch the threads. Keep pushing as you thread it, or you can damage the first thread if your not careful.
Put some assembly lube on the gear end, and your oil pump drive shaft gear and bearings, and enjoy.
