Show Chrome Backrest installation on F6B

Hello, ready to complete my Show Chrome backrest installation. Just wanted to ask if anyone had any helpful ideas on those slant spacers? I picked mine up used and it just looks like they could go all kinds of different ways. I know there is one for the top side and one for the bottom mount side. Just wanted to ask someone who may have already mounted one if there is a sure way they go. I know you can do it in many ways and it will work, but just would be a lot more simple knowing which way they are the angles are supposed to on both sides...and the mounting bracket has such a difference in heights , looks like the little slant spacers wouldn't get it line up correctly???thanks.