E Body ralley Instruments not working

Does an E Body with a ralley cluster have an instrument voltage regulator? I've done searches for any info on this. Classic Industries has them for the non ralley clusters but not for ralley clusters. My oil, water, and fuel gauges are not working. My instinct is the ivr. I can't readily see one under the dash but I cant see everywhere without starting to remove things. Is there one on ralley clusters?
Thanks
Arno

Have you checked your fuses with a test light?

Yes I have. Power to both sides of the instrument fuse.

The cluster voltage regulator is the same exact part for both ralley and standard gauges.

https://www.rt-eng.com/index.php/RTE_limiter.html

Both Classic Industries and Year One say they are not. Neither one lists one for an E Body rally cluster, but have it for a non rally cluster.

Finally found a pic of the back of a rally cluster. No place for an ivr. My wiring diagram shows one though.

Thank you Dayclona, that is very helpful. My service manual does not have that schematic. I am used to the ivrs that plug into a circuit board. This is different. Combined with the photo I found, I think I can just barely see it in the car. I will get it out tomorrow. Any idea how to test one?
Thanks
Arno

I gave you the link earlier

https://www.rt-eng.com/index.php/RTE_Limiter2_Faq.html

if you attach a test light to the sending unit, coolant one is easiest, it should blink.

at the gauge you should see the same thing with the key on of course.

you can verify the gauge with 2 AA batteries in series to make 3 volts.
attach those to the gauge posts and it should move to the middle.

I used a battery charger to test the vr once. instead of wiring it to a battery. you should see the output blink using a test light as well.

Thank you Bee1971, also very helpful! It explains the E body ivr is different from the others. It also says that it is not available through the aftermarket.

Thank you Andrewh, I have some troubleshooting to do this weekend.

OK, I got up under the dash and tested the instrument voltage regulator. It is working properly and appears to have been changed out to a new solid state version. The oil and water gauges I now believe are working, just not very responsive or accurate. I am attributing this to being 49 years old. The fuel gauge is still pegged empty. Grounding the sender does nothing. I found the fuel gauge to be wired backwards though. The 5 volt lead was where the sender lead should be and vice versa. Could this fry the gauge? I,m thinking it might.
Thanks
Arno