The 89/90 and 91's have to use either a magnetic signal tach, or one that runs of the alternator...(I know nothing about this set-up.).

On the other hand I had the magnetic set-up on my 89 motor. You mount two small magnets 180* apart on the harmonic balancer, then mount the magnetic pick up. Run the wiring and hook it up.

You will need a Tach that function on that type of signal as well. Geno's Garage has what you need.

 

The is also a magnetic pickup that can read flywheel teeth which is I guess another option.

http://www.summitracing.com/parts/sww-82646/overview/

 

I have the two magnet set up on mine for about 15 years. still works fine.

 

Is there a tach that works with that sender? it says it is a speedometer sender.

 

This is what I'm looking at. Look at the bottom of the page and it shows the sensor.

http://www.summitracing.com/parts/sw.../requiredparts

I'm wondering if the sensor you are using would work with this tach. I think it would.

 

Cool the sensor could easily be mounted in the inspection cover at the bottom of the bellhousing.

 

Yes, that is where I thought it could go. Weld a boss on the cover. The engine oil pan is big enough to hide it from road debris. My current plan is to do the suspension repairs tomorrow. Ball joint socket coming in today. Replace the cone air filter I currently have with my version of the BHAF. Then get my Redtruck engine back together. Then if nothing immediately needs attention do the Tachometer then 4" exhaust. I've ordered the dynamic timing piece, but they are on back order which is fine with me. I still need to install the pyro, boost and fuel pressure gauges. It truly never ends,,,, lol