plastic sender unit refitting

Has anyone got advice on refitting the plastic sender unit back into the tank off my 83 GTI ?
I removed the tank ages ago to have it cleaned out, and I am now having a nightmare trying to refit the sender unit.
Can anyone tell me if its a straight fit onto the tank itself or is there a fitting attached to the tank in order for the sender unit to attach itself to?
I have the rubber gasket but from trying to refit it I think I may have lost a fitting somewhere-

Rubber seal and straight fit. It is tight though so a block of wood and hammer may be needed to gently persuade it back in.

Hi

i've got a a tip as i found this dificult too.

Tools needed:

3/8 inch ratchet
3/8 inch extension bar (doesn't matter what lenght but i had a 10")

In the slots around the edge of the sender, you'll find that the drive of the ratchet will fit straight in quite snugly.

Put the drive of the ratchet in one, and the extension bar in the other (vertically) then lever the ratchet against the extension bar. It wiggles a bit the first few tries but once you get a good purchase on it it'll twist in quite nicely.

cheers!

PS using a block of wood and any impact methods (it hammer) will break the sender as the plastic gets brittle.

The tip using a 3/8 rachet and extension bar works a treat - i would recommend it to anyone refitting the sender unit - Thanks for the advice

Had to do it again recently so took a pic (incase the text wasn't clear)!!

I wish I'd known/thought of this back when I was rooting around in my tank. Went and snapped a few bits of plastic off the sender  

snapped my original one clean off. had a new one from crazyquiff and wasn't going to risk breaking another.

spend about an hour trying to fabricate a tool and give up. then… over a cigarette and a beer and gazing at the ****er trying to imagine how to get it back on… it struck me!!

presto!

by the way, the golf is now mobile again. but i'm too scared to drive it anywhere as i can't face it stuttering again. I know it sounds stupid but i can't face the fact that it may not be fixed and i'm seriously worried.

If it doesn't work now i simply do not know what to replace next!!