Find a GM chassis service manual for your 74. You're sure to need it to sort out the wiring issues. The instrument cluster(s)? should probably bolt right in. You'll need the correct sending units for guages. The question will be the wiring. You may need to grab the harnesses from a donor car too. If you can get the wiring diagrams, study them. This should answer this question.
A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!