Caddy fuel tank question

[rumbling_caddy]

So I'm finishing up a 1.6TD swap into a caddy.  It had a gas engine when I bought it.
I believe originally it was a diesel truck because I see the mount where a diesel fuel filter would be.

The last thing to take care is the fuel tank.  I see both hoses on the bottom side of the tank.  I see an electric inline pump and the smaller gasoline filler neck.I wondered if all I need to do it swap the filler neck to the bigger diesel neck and get rid of the inline pump.

Are Mk1 gas and diesel fuel tank the same?  Maybe I still have the diesel tank in this truck and some PO added the fuel pump and swap filler neck?  Normally on a gas truck the fuel pump in in the tank?

I should take a closer look and the other diesel caddy I have for comparison.  Does someone know for sure the difference between oem gas and diesel fuel tank setups?

[vic_vr6]

tank is definitely the same. not sure about the filler neck.

You can tell if the car was originally gas as the under hood fuel lines original ran to the drivers side on a stock gas (CIS mechanical fuel injection).

[CRSMP5]

if gas id pull and look in the tank... gas does bad things... also pull the screen so it cannot slime up... its not needed... your filter will catch more...

mod the filler neck...

remove pump stuff...