Switching from gas to diesel fuel tanks

[pat english]

I can only find threads on people switching from diesel to gas or switching from gas to a duramax..
I'm switching from 454 gas to the 6.2 diesel.My truck has 3 gas tanks.I'd like to delete the 2 side tanks and just use the one in the back.What would i need to do?I will probably buy a new tank for the rear anyways because it's been sitting with the cap off for over 20 years.
Are the tanks the same but with different sending units?Thanks,Pat