Wheel Cylinder Question

I am replacing the left wheel cylinder on my 97 Caravan. The man at O'Reilly Auto Parts told me the right and left are the same. When I looked at their website it shows two different bore sizes for the left and right. The websight shows the one I was sold is for the right side. Can someone please give me some accurate information on this?

the bores are the same side to side. you will have either 13/16 or 3/4. If I remeber right you can pull the piston out of the old one and they should be stamped what size they are.