11" drum rear backing plates

Hi all, I am wondering if anybody can tell me if these are the early - up to 1970 or later, 1971 and up backing plates for the rear brakes - 11". I need to buy the brake strut lever and I see there are different ones for the early and the later backing plates with the split coming between 1970 and 1971. I sent the photos to a well respected Ebay vendor who sells the levers but he could not 100% tell by the photos. I just want to order the correct parts the first time and be done. Any help is appreciated. Thanks, Rob

It looks to me after comparing photos on the internet and Ebay, the difference I see is where I circled. Others appear to have more meat in that area. So, it looks like these are later, maybe much later than I thought?

I think there are three different 11 inch backing plates and brake drums depending on the width of the shoes, 11.0x2.0, 11x2.5 and finally 11x3.0. Maybe not but I'm sure I've seen all three sizes, mainly on C bodies, maybe on some B body with the H.D. brake options chosen when it was built

I think the earlier parts were left and right, the later plates were universal and have 2 holes for the emergency cable

Thank you for the replies. Check out these two Ebay auctions - this is what is confusing me. One is up to 1970 and the other starts at 1971. I see the 1971 to 1975 is curled but not sure why?
Links:
1965 to 1970: https://www.ebay.com/itm/234795457116

1971 to 1975: https://www.ebay.com/itm/334641818073

I do not think they are twisted I think the support rib has the parts laying at an odd angle.

This is the rib on the 71 and later bar. I think the only difference in the two is the rib was not here on the 70 and older bar.

I think the bars are interchangeable as long as the rib clears the wheel cylinder.

Thank You, if I do buy the ones you pictured and if they do not fit because of the rib, it can be removed.