Apologies if this is a duplication of info.
Have been idly looking around interweb on this topic and came across Big Dog Motorcycles. Their Wolf version uses thev121 Vi x wedge motor. They advertise cam belts, also suited to M3W. Kevlar reinforced.
May be a helpful source for engine bits. Didn’t see if they had crank sensor though. They show on eBay one but explicitly not for xwedge

Do we know what the technology in these is for our engine? Is it a Hall effect device picking up pulse(s) from the crank...or what? Might widen the search options for replacement/repair

Wikipedia says this:

There are several types of sensors that can be used: the inductive sensor, Hall Effect sensor, magnetoresistive sensor, and optical sensor. Inductive sensors have the simplest construction and are usually purely passive devices. Hall effect and magnetoresistive sensors have the advantage over inductive sensors in that they can detect static (non-changing) magnetic fields. Optical sensors do not have great resistance against fouling but are able to provide the most precise edge detection.

I was fortunate enough to buy a spare one before they all disappeared. There was a helpful thread here about what we should grab before they disappeared. Some pictures of it below.

Looking at it, it is not optical, as the end is solid with a small metal centre. It is magnetic, as the supplied washer was sticking to it, but beyond that I can't tell much. There are no visible markings or identifiers on it.
Good luck with the search!

Big Dog motorcycles does stock a sensor that will fit our Three Wheelers.
The Big Dog part number is BDM170-00382
S&S number 55-021.

They say the difference between 106-0734 and 55-01 is that the latter has a slightly longer wire but the sensor is the same.

I have one on order and will update once I have received it.

Good info Lance, thank you.

Yes, very encouraging. Please do let us know what turns up.

Thank you Lance | Please keep us updated on your progress with S&S Part

I did have the opportunity to speak with a tech at S&S yesterday. His comment was to keep checking the S&S website, especially towards the end of the month (July). S&S has commissioned to produce additional inventory of Part # 106-0734. I hope it is true information.

Hopefully I am wrong but if you Google that part number and go to Big Dog website then

1/ Sensor body looks far too short (AKA Harley type)

2/ Cable exit from sensor body shown would foul on crankcase - needs to be rotated 90 degrees....

I am reliably informed that MMC will have a delivery of these from S & S in the next week or two 🤞

Stevo666, Just received my part from Big Dog, and you are correct, it is not the correct part for our purpose.