I just did mine in my 90. Used some eBay specials. They aren’t the highest quality gauges but for this old truck they work. And they only cost $180. I had the same problem as you, Speedo was dead, as were the oil and temp gauges yet all had signal right to the cluster. I did have to buy senders for the oil and water to match the impedance of the new gauges. The others hooked right to the factory wiring. I even wired in the dummy lights, brake, ses, alt, oil. It took a little time plus building the cluster but turned out decent.
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