Perhaps it's a Kjet / Digifant thing? Got to say when I was looking over the thread some of what I was reading / the images weren't as I remembered mine (1992 8v). Picture angles are awkward and I'm struggling to compare like for like. It's fitted now, these are old images from around 2x years ago.
That Looks nothing like mine. My cars a 87/88 16v. I believe my car was at a change point where more 'super seeded' parts were being produced and swapped over. I suspect mine could be the same as the mk1 golf, (K-Jet too I think). My sender unit is soooo much slimmer than that. I bet mine and Cressa'a sender units doesn't have that 'bellow' mention on page 1.
That Looks nothing like mine. My cars a 87/88 16v (K-jet). I believe my car was at a change point where more 'super seeded' parts were being produced and swapped over. I suspect mine could be the same as the mk1 golf, (K-Jet too I think). My sender unit is soooo much slimmer than that. I bet mine and Cressa'a sender units doesn't have that 'bellow' mention on page 1.
Does the MK1 have an in-tank pump? There's an inbuilt swirl pot arrangement on mine (1.8 GTI '83) that's part of the inside base of the tank. Fuel exits via gravity to the external pump as opposed to having to be moved up and out the top of the tank? I've just the gauge sender gubbins. Cressa's is definitely Kjet, maybe has more images.
There is a pretty clear pic I posted of my unit on page 3 where you can almost see the full unit. Mine has 3 wires connected at the top, where as yours has 4 wires. Judging from the info I found on 7zap, the in-tank pump came in around '84. https://volkswagen.7zap.com/en/rdw/golf/go/1984-14/2/201-69000/ Could just be a case of early and late mk2 parts. Maybe the change from CE1 to CE2 wiring had something to do with it? Can't really think of any other reason bar voltages and pressures etc.
Only question on my mind now is... when did they implement that other sender unit design into the mk2?
Yes the lifter unit changed from ce1 cars to ce2, 3 pin to 4 pin. Exception is cars which had digifiz cluster, these also had a 4 pin sender for all years with different part number to ce2, not sure on difference but guess it's just early design with 4 pin plug on
I believe that shiny metal thing is the original part having the reducing rubber hose. Obsolete and doesn't like our latest fuels anyway.
The shiny thing is on 90spec, pre-90 it just had a large hole with a rubber seal tube thing pushed into it, then the pump is pushed into that. I found some good images last night will upload later, including the digifiz specific 4 pin lift pump I mentioned which is only used on pre-90. 90 spec it just uses the same one as normal GTI
Might be an answer https://jaaattengineering.co.uk/onl.../jaaatt-engineering-in-tank-fuel-pump-reducer
I re-did my MK2 16v fuel sender a while back and found AN-6 Stainless braided Teflon line fits a treat (and totally fuel resistant). https://www.ebay.co.uk/itm/360848182950?hash=item54043a4ea6:g:-YMAAMXQVERS6Mc7