I had my mechanic replace the gas gauge sender unit in my '75 (I did not want to drop the tank myself. . .), and when I got it back, the fuel filler opening was towards the back of the fuel door.

He took another look at it and could not see how it could not be in the correct location.

Has anyone any ideas of how the tank could have gotten shifted a few inches towards the back of the car?

I really don't have anything.  First thought was they installed it backwards, but then the fuel lines wouldn't match up.

Then I thought since it's just strapped down, maybe you could loosen the tank straps and shove it forward.

That's all I got and it ain't much.

Good luck.

*edit....Then again, I didn't have to do anything to the tank when I replaced my sender.  Mine was on the bottom.  Not sure about yours.

Yea, the earlier ones were on the bottom, mine is on top.

Like Gary, my first thought was they installed the sender backwards, but...the fuel lines would be on the opposite side, so....that's a bust. The tank should cradle up into the frame by itself, as far as forward/rearward. I could see it being off a little right/left tho. I'd agree with Gary....loosen the straps, and see if the tank can be maneuvered into the correct location....it may just be tilted a bit, and throwing the top to the rear.