It's that time again where I want to update my fatty PSP to the latest firmware so I can play all the latest games!
Currently I have 5.50 GEN-D2.

So before I ask "what do I do?", I've searched around and found this post which seems to fit my case since D3 doesn't seem to be too far off from D2.
What got to me though is that it referred me to THIS THREAD which states a list of working CFWs to update from. To my surprise, it doesn't specifically state 5.50 GEN D2.

What course of action do I take?