measuring question 8 3/4

looking at this chart http://www.bigblockdart.com/techpages/diffchart.shtml whats the flange? is that the piece that goes around the drum brakes? or do I need to take off the brakes to get this measurement? I know some say that the chart is wrong and that from flange to flange its 52 5/8 or something like that!

I also read that I can still use it if its a b body 8 3/4 I just need to force the leafs in or move the perches! The question w/this is will my wheels stick out when doing this? Even w/a big offset rim? remember I have a 73 Dart Swinger so the wheel well is a little shallow!

Please shed some light on this subject for me!

Thanks
Jason