I was wondering if anyone has had any luck with a VSS sending unit you can screw onto your cable speedo drive to run an electronic speedometer. Several people are selling them for what looks like a very reasonable price just wondered if they worked for you.

 

They work fine. They put out a 4 pulse square wave that Toyota electronic speedometers are looking for.
I've installed two in custom installations.
The first one was in a 84 Suzuki SJ410, VW 1.9l. diesel Toy transmission, t-case and axles. 2003 U.S. 2wd pickup speedometer grafted into the Suzuki cluster.
#2 1989 Samurai 3rz-fe 2.7l. Tacoma engine, r151f transmission, 23 spline t-case toy axles.
2004 Canadian toyota corolla electronic speedometer grafted into the Samurai cluster.
My samurai registers 7-10 kilometers slow, but that's due to 4:88 gears and 33" swampers.

 

My use wasn't quite as ambitious. I'm using a 94 SR5 cluster in a 89 pickup. I've moved the 94s engine, computer, harness and instrument cluster into the 89. Adding 2 wires into the 89s body harness should complete the system but so far I haven't been able to get any movement in the speedometer. Just kinda checking to make sure they worked.

 

I've used the one from marlin crawler twice in motor swaps and worked flawlessly both times.

 

Someday when I somehow come across some money I plan do make a custom gauge cluster for my 87 4Runnah. I am a stickler for instrumentation and would LOVE to have full sweep gauges everywhere. (That are actually accurate is a plus too)

I've mocked up a panel and you can fit the 2-1/16" voltmeter, coolant temp, oil pressure, and fuel gauges and 3-3/8" speedo and tach gauges. There is just enough room left in the middle for a 2-1/16" wideband O2 gauge.

The only thing that is somewhat tricky is the need for an electronic speedo. I'm glad the OP asked this question as it was one that had been on my mind for a while. Good to know the converters work. I had been eyeing the Marlin one.

 

I picked one up for $20 at Low Range. It came in a Trail Gear box. So far I'm still on jack stands but I haven't been able to get any indication on my speedometer. I'm a little nervous to do anymore then 1st gear idle so I may pull the speedo drive out and run it with a drill. Any other troubleshooting ideas?