How tell difference between a 69 and 70 rear end/axle?

[scottv]

I'm looking at getting a 5-lug conversion kit to change my current 6 lug rear to 5 lug. But it looks like there is a difference in kits between a 69 and 70 year rear end. My truck is a 70, but I'm not for certain it's the original rear so I'm wondering if there is any easy way to tell the difference between a 69 and 70 so that I order the right conversion kit for what is on the truck? Thanks!