Another Blazer tank swap Q for LWB trucks

[OLDIRON69]

I have a Blazer tank to put in my '69 LWB, I have read the entire FAQ section on the install. I still have a question as to the rear crossmember. For the tank to fit between the rails it looks as if I will have to cut out the rear crossmember, the one where the tail light harness runs into. I have a reciever hitch bolted to the frame so I'm not worried about rear support being an issue. I have the sender, straps and fuel line....oh, and sawzall in hand Any help would be appreciated. Oh, the Blazer tank is the one from the surplus military place, so it's a 73-up Blazer tank.