Is the in-tank fuel pump accessed from the trunk/wagon compartment or from the underside of the car? I can't find the square latch that holds the in-tank fuel pump. I'm wondering if anyone has a photo of exactly where the in-tank pump is. Thanks in advance.

For a sedan, there's an access plate (to the top of the tank -- you have to then remove the exposed bung nut to open the tank and pull the fuel level sender and in-tank pump hardware) under the carpet on the hump in the forward portion of the trunk.
For a wagon, you have to remove the "plywood" panel on the floor of the station wagon's rear compartment (I can't remember if you also have to remove the rear seat). There's an access plate, just like in the sedan, underneath which is the access to the tank.

On my sedan, square metal plate, driver's side foward section of the trunk. Bung nut below, wire harness coming from that.
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85 240 DL, 89 245 DL, 432,000 miles total

The in-tank is accessed from the interior. Lift the carpet in the trunk or remove the board held down by screws in a wagon. Remove the metal plate through which passes the wires. Then remove bung nut on top of tank.
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1980 245 Canadian B21A with SU carb and M46 trans