It has a conversion for fuel gauge relocation but has not been tested. The tachometer is a easy hook up positive, negative and tachometer signal. This is a very nice gauge in my opinion but is used.
It should be plug and play for 78-80 but can be used in later model squares. The earlier 73-77 would need some modification to work since earlier versions had AMP gauge and mechanical oil pressure gauge.Here is a good read on different GM truck tachometers and the differences. The item "Chevrolet GMC WORKS Dash Gauge Cluster Tachometer Truck Blazer Sierra Silverado" is in sale since Thursday, August 12, 2021. This item is in the category "eBay Motors\Parts & Accessories\Car & Truck Parts\Interior\Dash Parts".
The seller is "79trans-am-guy" and is located in Loveland, Colorado. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, France, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Antigua and barbuda, Aruba, Belize, Dominica, Grenada, Saint kitts and nevis, Saint lucia, Montserrat, Turks and caicos islands, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Pakistan, Paraguay, Reunion.