Yeah the seat belt light is just on a timer...

IVR as mentioned is instrument voltage regulator & it's is the little box on the back of the cluster that has a little jumper harness that attaches to three gauges, oil, temp & fuel.. Well in this case it attaches to oil & temp.. The blue wire from the low fuel relay provides the voltage for the fuel gauge..

"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."