Identification help needed: Early SW Tachometer with distributor driven sending unit

I have one of the early SW tachs which require the sending unit that goes under the distributor cap. They are not all that rare, but they hardly ever come with the sending unit.
I know at one time the sending unit was stamped with the code which indicated the application, but the white ink stamping is almost completey gone.

Can anybody identify what this is for? The strange thing is that the male and the female side of the sending unit don't seem to have the same diameter (will have to measure again) which means it's not just meant to go between a stock distributor and the matching cap.

Maybe anybody can identify or tell me what dimensions I need to check for.





thanks!

 

Bttt

 

Let's try again...

 

At 4500 rpm it may be an industrial unit or truck.

 

All you need to read is the last letter of the part number and I'll be able to tell you what it fits. Can you read that?

 

Will try again although it's unlikely. Will also get some measurements. Were these originally for car or commercial use?

 

I can't help you with the application, but I run this set up in the Lazy 8. Mine is made for a mallory dizzy. Originally the car had the same set up for the 56 chevy dizzy. I have seen them also for Studebakers. Your right about the senders, very tough to find! Can you modifiy your dizzy/ rotor to make it work?

 

Here, I'll just print what my 1960 catalog says:

762-H Auto-Lite, 6 cyl, 1951-53
762-J Auto-Lite, 8 cyl
762-K Delco-Remy, 8 cyl, (except High Tower)
762-M Delco-Remy, 8 cyl, (High Tower prior 1957)
762-P Delco-Remy, 6 cyl, (High Tower)
762-S Mallory, 4, 6, & 8 cyl
762-AA Auto-Lite, 6 cyl prior 1951
762-CC Ford, 6 cyl, 8 cyl prior 1957
762-DD Delco-Remy, 6 cyl (except High Tower)
762-R For use with built-in tachometer take-off. Order appropriate drive tip.

 

I have the same tach [no sender] only mine goes to 8000 rpm. Was planning to dis***emble it and use guts from my electronic Autometer in it's case...not too sure on how to adjust the two shift-point needles tho.

 

Thanks for the info. I measured the inside diameter of the lip (female side - last picture) of the sender at 3.5". Tried hard but could not read the ink stamp anymore.

I am running a flathead with the crab style distributor so using this is out of the question because I don't have the fan clearance. I am running a prewar mechanical SW tach for which I made a crank drive.

 

The part you have is called a "Distributor Switch." I'm looking for a 762A or 762M if anyone has one available.