I used the standard SW senders.
the outboard one is per plans.
The inboard one has an electrical bulkhead terminal installed into the sender plate.
Access is tight so I found the smallest one I could.
The stud is around 3/16, the hole in the plate is 1/4 an the OD of the delrin bushing halves is probably 1/2 or maybe 9/16 - I didn't measure it.
It didn't come with any specs or instructions so I had to work my way up with drill bits slowly on the first one until I had the right size.
The bushings have a step to keep them centred and a Viton Oring on each side.
I had to neaten up the phenolic insulator on the inside of the sender to push the passthrough as close to the centre of the plate as possible.
Then I bolted it up, crimped some AWG14 onto a ring and prosealed it throughly. Don't trust the thread leak path.
The other end of my AWG14 is soldered onto the sender where the chassis ground used to be. I removed the original black wire grounding the sender.
So the signal wire from the outboard sender effectively becomes the new ground for the inboard sender. Its important obviously that this doesn't touch any part of the airframe and that you remove entirely the ground side wiring of the original inboard sender.
The access hole had to be dremeled out a touch to make room for the passthrough. you don't want to overdo this. There's still about 1/4 of prose gasket there.
Calibration was straight forward. I opted to calibrate in 32x5L increments out of curiosity to see what the curve would look like. I forgot to take a photo of the curve. ill update this thread with a photo next time I get a chance.
One thing I noticed is that you need to be patient with waiting for the fuel to drain inboard, and you need to give the wings a wiggle up and down to make sure the sender wipers move. I suspect they need some wearing in and/or stationary on the ground there can be just a smidge of friction. In flight I'm sure motion/vibration would negate this.
Ive flown 2h and had the tanks sit full for 3 days with no leaks so I'm calling it good. In flight, the totals remaining on the tanks + Fuel flow used have been within 1/2 Gal of total useable so I'm pretty happy. ill see how it is further through the range as I've only burnt 70L (15gal) so far.
Ive scribbled a diagram at the bottom as well. sorry the photos aren't in order.
Hope this is useful!