Underneath housing its leaking fuel. Can i unbolt it in one piece and turn it over

 

Can't easily turn it over because of the 2 lines connected to the bottom and the 1 on the rear.

But yes you will need to remove the fuel lines from the filter housing/manager to remove the fuel heater and reseal it-do the water in fuel sensor on the rear at the same time and consider replacing the water in fuel drain line and IP line at the same time as well.
Both of those O-rings are common leak locations.
The IP line is not available as a molded line anymore so most jus run a new diesel rated line under the intake and bring it back up above and make a loop to get it going the proper direction back towards the IP inlet.

You might want to do the "feed the beast mod" while you are at it?

 

Looked up ftb mod I've gotten pretty much just 1/4" to 3/8" is there drilling tapping?

 

Yes there is.