tachometer?
 

I was just wondering if i could use any brand of tach (canadian tire brand) would work on a 92 1st gen , and if so how would i go about installing one

After you install a pickup to make the electrical signals for your engine, its a done deal. But, to get any tach you want to work, you'll have to install a hall effect pickup. You can get these thru Dakota Digital, IssoPro, and several others. I always mount my pickup in the bell housing area to pickup the flywheel teeth. But, if you don't want to go thru all that, there's a pickup that mounts to your alternator. You can get it thru Autometer.... However, you can get The 4500 RPM Diesel Tach and the pickup (Sold together as a kit) for a little over $100 from Autometer....

Go to the price quote section, type in what you want. I was told my 92 has a sending unit for a tach when I requested a price quote on some gauges

The Trucks have pretty much a universal type wiring harness that spans several models. The Diesels that have the tach option are pretty well plug and play. If yours don't have the pickup and you can get one, it'll plug into the harness..... The aftermarket tachs are usually cheaper than foolin around with Dodge....unless you've got a donor truck.

How likely is it to already have a sending unit factory installed already? And where would the hook up be located?

Sorry, been away at some tractor pulls, one of my customers having problems. Anyway, look in your repair book, under the electrical section. Isspro tach install - Dodge Cummins Diesel Forum 1stGen.org • View topic - Early Dodge Cummins Tach. ISSPRO Tachometer Sensor Kit for 1st Gen. Dodge Cummins and other vehicles