On 1975-82 Corvettes the integrated circuit board is the culprit on 95% of non-working tachs. Replacing the ICB can be accomplished with ordinary hand tools by a competent do-it-yourselfer.
We'll find it for you. Give us a call at 313.499.0500 and we'll source that discontinued or hard to find part. Motor City Corvette Parts always recommends professional installation of our products. Buyer assumes risk of damage caused by improper installation.