Gauge Cluster with Tach

[cirose]

i put a tach/fuel guage all in one combo in my 87, just changed out the entire cluster it was plug and play and worked fine

[Tazman]

I will try to put a picture of the final. All I did was pull the dash and the gage cluster. Then I took my dremel with a drum sanding tip and just opened up the hole till the tach fit in nice and snug. I am kicking myself for not thinking of this sooner, it was that easy. Sorry it says my picture is to big, will try again.

[SouthernBrandt75]

Sweet thank you!

[75gmck25]

The original GM tach clusters can be swapped in if the years are a close match, but will not be an easy swap with mis-matched years. 

For example, my '75 GMC had a mechanical oil pressure gauge, electric ammeter and electric temp gauge (no tach), and I was able to directly swap a tach cluster from a '74 Suburban.  In the '74 Suburban cluster the tach replaced the large fuel gauge and a small fuel gauge replaced the clock.

I believe that clusters from 74-76 are the same, so any of those years would have worked in my '75.  If I had tried using a cluster from later trucks I would have needed wiring in the truck for an electric oil pressure gauge, and wiring for a voltmeter instead of the ammeter.

FYI - the GM tach wiring for my truck has a separate three wire plug that is in addition to the large multi-wire plug for the cluster. The three wire plug provides power, ground and RPM signal to the tach, so adding the factory tach in '75 did not depend on the cluster for anything but mounting.

Bruce

[hatzie]

I found a post that said it will is basically a plug in and go up to 1986. It won't work in a 87 cause of the computer. Also if the truck has a factory cruise control that wont work either.

The 1987 cluster is still mechanical!!!  Just because the RV series have TBI is not seriously problematic.  The gauges are mechanical all the way to 1988 and only some of the 89-91 clusters have electronic speedometers.
You will get into trouble if the optical VSS is your only speed signal because the 1980 & prior clusters didn't have the slot and the earlier speed heads didn't have the mirror or the spinning chopper wheel.
Fonts changed in 1980.  That's just looks.
The temp sender will need to be installed out of a 78-81 or the bias resistor from your 1987 gauge installed on the 1978 temp gauge.