Anyone know if I can use a 123 sender from an 85 300D in a 81 SD?
I'd like to at least try and test the circuit by installing the sender in the 81 or plugging it in to test the circuit.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

It shows up on the part's store listings as the same part so it looks like it'll work fine. I got a new VDO sender for pocket change over $50 at bma auto parts, just have to get around to installing it!

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

For tyhose wishing to know you can use a 123 sending unit to test your system but it willnot work long-term unless you do not need accurate readings from the fuel tank.
I connected a 123 unit to my tank and it will only read down to 1/2 tank so the resistance in this unit must be different from the 126 units.
I went to the local wrecking yard and got one from an 84 SD and it works. So you can test your guage on the dash but it is not recomended to use the 123 sender.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Interesting since the parts catalogs used the same part number for both. I just installed mine, before swap I had about a sixteenth of a tank afterwards I have closer to a half tank. I'll fill it up today but I suspect that the half tank is a lot closer since I don't even have 400miles on it yet.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k