Speedometer Sensor 1981 300sd
 

I dont post much here as most of my inquiries are already answered in other threads, but spend hours learning from all of you weekly. In the past year I have acquired an 83 300d (170k) and just recently an 81 300sd (151k). I think my garage is a german taxi shelter as they are both ivory. I have used the search function and found many solutions to the common problems you all have had with both models, which has saved me mucho money on repairs.
My latest project is restoring the cruise control in my 300sd. I have just installed a rebuilt amp and new actuator and still get nothing. I have replaced the bulbs with the correct Osram bulbs and checked all connections and fuse. I am going to order a new cruise switch since all else is new but while I am ordering, want to order a speedometer sensor. Where is this thing on the early w126 ? I have taken my instrument panel out and dont see anything obvious.
I have used the SEARCH function and nothing really addreses where and what. I have looked on some parts websites which show a photo of a impulse sensor....is this the same while another shows one that resembles the tach amplifier? SO...
1. Where is this sensor ?
2. What does it look like?
3. Is this a job for a more experienced mechanic ?

Thanks

the speedometer sensor is an electromagnetic pickup on the upper rear of the transmission, driver's side. A single M6 screw (with 10mm hex head) mounts it.

Take a good look at it. There is a thin black wire that runs into the end of the pickup. It can get pulled off too easily.

thanks for the info...I will check out before I purchase.

Seems like every time I try to do a simple fix of something the end result is a parts order, upgrade of my toolbox and a vast knowledge of the system I am working on through this forum and my CD manual. I have learned so much from all of your posts. Thanks again for your kind replies !!

So I take it the sensor should not freely spin with the wire sort loosely attached, then?