Plan A:
On Ebay I found a very cheap (15 Euro) oiltank with oillines for the 43F.
I knew (thanks to Mezo) that the oilfeedingline leaves the oiltank at a far better/safer location than on the 34L-tank.
The tank came ... and wasn´t in a good state. One eye for the attachment on the frame was broken and the other was heaviliy
soldered/repaired:

but at least I had some good oillines...
After a while I found another oiltank. It was the one Mezo had shown in is "better oiltank"- discussion.
It was also cheap ...

... but in better shape (as you can see !)
The tank had some homemade modifications on it:

A temperature sensor.

And a oillevel- indicator.
So I started to disasemble the bike in order to change the oiltank, lines and oilcooler...
This is what I found:

Here should be the Oilfeedingline coming out.
I looked under the tank... and saw this:
... somebody changed the tank already...grmmmph. (Or has the 34L built in ´84 the 43F tank ? Karl ??!!!)
So I ripped off the oilcooler and changed the upper oilline and was done:

Make shure you are holding the joint while unscrew the oilline. This way you don´t stress the tin/soldering to much.
And this is what I saw:
The carbi !!! Here he is !!
Next project:
TT Chokeknob
Fred