Picking subselection randomly if true

I've been chewing on this issue for quite a while, and I finally decided to make a demo spreadsheet and throw it out to you smarter VBA folks. All the data on the spreadsheet is made up (which took longer than I thought it would).

Basically I get a list of about 500 accounts, then I apply a macro that puts the word TRUE next to accounts that meet certain criteria. From there I want to randomly assign a number of 1-20 to accounts that have the word TRUE in column M (replace TRUE with a number). I can't have the same agreement number pulled twice, each record with a number 1-20 must be unique (you'll see what I mean in the spreadsheet).

Basically my end goal here is to have a macro that randomly samples 20 different agreements out of many that meet the TRUE requirement.

Thanks in advance for your help, my brain is killing me.

Thanks for the reply! I tried doing that, however, when I sort it puts duplicates in the first 20. Also, I need a macro that will automatically replace the word true with a number. (I have to automate this fully). Thanks again!