Gary, give them a call, and ask if they'll give you credit on the correct part, if you send that one back. I would say they will, since you didn't use the part.
You have to watch on all H&R guns, as they had design changes in all their firearms over time, even though they looked the same externally. I've not paid much attention to them lately, since Remington bought them. I imagine that they also added their own touch on a lot of the parts since then.