Alright, I'm mostly writing this post so I can link to it from my shop over in the marketplace, but I imagine it will be helpful for others as well.

The first step in determining your motherboard and dash version so you can know what type of hacks you can do it to determine if you have a phat or a slim.

Use this image as a guide:



Now, if you have a phat - take a look at the power socket on the console and compare it to this image:



If you have a slim, take a look at the power socket on it, as well as the sticker on the back for the power rating and MFR date and compare to this image:




Alright, now you should know your motherboard type. If you have a slim, you can skip determining your dashboard version as all slims are RGH2 no matter what dashboard. If you have a phat console, determine your dashboard number by following this guide:



Finally - now you should know both your motherboard type and dashboard number so here is the all inclusive list of what can be done with each console type:

Xenon (dash up to 7371): JTAG'able
Xenon (dash 7371 to 14699): RGH1'able (***for DVD key recovery only! I do not perform this service personally)
Xenon (dash 14719 and up): No JTAG/RGH possible at all.

Opus (dash up to 7371): JTAG'able
Opus (dash 7371 to 14699): RGH1'able
Opus (dash 14719 and up): RGH2'able

Zephyr (dash up to 7371): JTAG'able
Zephyr (dash 7371 to 14699): RGH1'able
Zephyr (dash 14719 and up): RGH2'able (***RGH2/RJTAG Not very stable on Zephyrs - I do not perform this service personally)

Falcon (dash up to 7371): JTAG'able
Falcon (dash 7371 to 14699): RGH1'able
Falcon (dash 14719 and up): RGH2'able

Jasper (dash up to 7371): JTAG'able
Jasper (dash 7371 to 14699): RGH1'able
Jasper (dash 14719 and up): RGH2'able

*****NOTE: RJTAG can be used in place of any RGH2 service on phats*****

Trinity (any dash): RGH2'able

Corona (any dash): RGH2'able

**NOTE: There is a very, very new (MFR date 6/2014) "Winchester" slim motherboard that is not yet RGH'able. But basically nobody has these. As far as I know they are only the blue consoles that come in the FIFA 15 bundle and the console is blue.