I have recently done a V6 to V8 engine swap in my
91 RS. I knew I would have to get a V8 gauge cluster after the swap was complete, so I found a gauge cluster on ebay that a guy said came out of a 305 89 camaro. My first clue should have been when he said 89 and had a picture of either 90,91 or 92
cluster. So I purchased it and was happy. Until it
arrived and I only saw three tongs in the back of the cluster. Hears my question, could I gut the cluster that was in my camaro. Use one of the extra metal tongs in the fourth hole and run a copper line to one pulse receivers. Would this work?

 

Your original tach has 3 prongs because it only needs power, ground, & a tach signal.

The round ones from 89-prior also have the oil press. gauge which is the reason for the 4th prong.

I'm not exactly clear on what you're wanting to do... are you wanting to put the older tach in anyways ?

 

Okay, I thought I knew what I was talking about.
How can you tell the difference between a V8 gauge cluster and a V6 gauge cluster. I read somewhere that if the tach had four prongs in the back it was a V8.

 

I want the tach that I bought to read four pulses for a V8. I thought it was a V6 gauge cluster, but I'm not 100% sure.