coolant/fuel gauges both out

i have an 85 diesel golf. the instrument cluster works fine including: speedometer, LED lights, and clock. but both the fuel gauge and coolant temp. gauge both have their needles dropped to zero at all times...they just don't work. does anyone have any ideas before i hack anything to bits and install performance gauges (stock instrument clusters are no easy thing to find these days)? if not, what are some good performance gauges that would fit my car?
thanks
helicA

Are you sure it's the gauge? Have you taken the temp sender wire & grounded it to see if the gauge goes up ("ignition" on)? If so, then suspect the voltage stabilizer on the backside of the cluster, plugged into the plastic printed circiut sheet. For used parts try:

http://www.car-part.com