The one I need has a different part number, but the website says this is the replacement for the my gas water heater, so I bought it.
Then, I found that the pilot tube and thermocouple wiring were too long, I ended up just bend them into a loop and this does not affect the function.
If you are DIY, you would most likely need to bend the bracket holding the over-temperature breaker to make it work. This is not difficult, just need to check how the old one fit and keep the space between "pilot tube, ignitor and the thermocouple " and the burner relatively the same.
My old thermocouple was like 15 years old and it no longer keeps the pilot ON. I was able to bend its wire feed to the control valve to keep it working for about 5 days and it would stop working again, so it is obvious that I need to replace it. I was thinking about just buying a generic thermocouple for about $12, but since I have no experience with it and I do not have a torch to do soldering, so I just bought the whole assembly to save time.
I also replaced the anode rod, which was used up down to just the wire. The most difficult part is to break loose the old rod, so make sure you have a breaker bar with at least 24" in length. Also, for my case, turned off the main water shutoff instead of the cold water inlet to the heater (mine was 40 years old and no longer worked, don't ask how I found this out...).