I thought I would ask this here....88 f350 7.3 .
My temp gauge seems to have quit working, fuses seem fine, new thermostat seems to be working as it should, new temp sending unit, thought the new one I purchased was a dud so bought another one, still no go. I did the wire to ground test, still nothing.. It could be the gauge I guess....is there an aftermarket temp gauge that would work?

 

Any aftermarket gauge will work. Just find a port on the heads and install your probe (usually comes with a brass bushing).

 

This is the coolant temp gauge that I installed in my 86 f250:

https://www.summitracing.com/parts/atm-2607/overview/

I put the temp sensor in a coolant port on the head between cylinders #6 and #8. I also used the coolant port on top of the water pump for my electric fan. Either port will work for a temp sensor. Here's a thread I started when my truck had a bad thermostat:

https://www.ford-trucks.com/forums/1...erheating.html

 

I was wondering if I can get a temp gauge that simply attached to my already existing sending unit.

 

I'd just go mechanical and never look back, factory gauges were never accurate. It'll come with a bung to replace that factory sender and you only need power for the light.

They do offer electric gauges that can utilize the factory sender. I had one off of fleabay called a dragon. It was a cheap Chinese one but worker really well until I went full mechanical for both the temp and oil pressure.

 

x2

The only drawback of an aftermarket gauge is that you have to drain the coolant to install it properly. This really isn't a big deal. The radiator has a petcock you can open to drain the coolant.