Help finding a part

My house shut off valve is now leaking, so I can't turn my water off without going out to the main shutoff at the street. However I can't seem to find a direct replacement. It's a male 1 inch 90 degree to 3/4 female. Anyone know where I can find it?

I can't imagine why anyone would go to the bother of even making one. Logically, it has no function. When you install a valve, you usually want the same flow on both sides. If you wish to make a restriction/reduction, you do it before or AFTER the valve. How about a picture of your valve so we can see if it is some proprietary element.