Tachometer issues

[jlmerie]

I have a 1978 GMC truck with a V8 in it. I have a tachometer cluster that I have had for a while that I was going to put in this truck. I had not paid attention, but as I look closer it appears that this tach cluster may be for a four speed truck. I looked, and there is no PRNDL indicator on it. I think other than that the tach is correct for the truck. Can anyone tell me if this cluster is correct for 1978 and can I convert it for an automatic by putting the PRNDL indicator from my existing dash? The gauges and everything are in really good condition so I would like to use it if I can.

[old Rusty C10]

you may be able to use the white piece from your guage cluster and set the guages and the rear circut board from this one into that.. its been a while since i did this but i think youre missing a piece from this to screw in your gearshift indicator from one to the other

[knightlife]

bevel it out... a dremel is an awesome thing to utilize

[boatpuller]

here's one out of an auto.

[68GMC454]

thats the guage cluster im hoping to find..but im also thinking of going with after market gauges...looks like a nice cluster

[Prong]

IF the Oil gauge is electric, you're 90% there. That speedo has only 1 indicator light at the bottom. Does your existing cluster have 2? And are there spots for 2 on the back of that tach cluster? Can you post a pic of the back of that cluster?

[Captkaos]

Originally Posted by jlmerie

Can anyone tell me if this cluster is correct for 1978 and can I convert it for an automatic by putting the PRNDL indicator from my existing dash? The gauges and everything are in really good condition so I would like to use it if I can.

It appears you are just missing the gear indicator which you can swap.
If the oil pressure gauge is NOT mechanical (actual tube going to the engine block) it should be the '78-80 version.

Originally Posted by boatpuller

here's one out of an auto.

The picture you posted is NOT a 1978 cluster. It is a 73-75 cluster due to the fact it has an AMPS gauge on it

[jlmerie]

Prong, well it looks like I am not 90% there. The oil gauge is NOT electric. My current speedo has two lights at the bottom, but the cluster in the picture appears to have a place for the second light. Maybe this is not the best place to start to add a tach to my truck. I will try to post a picture of the back of the cluster a little later. Just in general, however, are the tach's pretty much interchangable between a four speed and an automatic if you have the PRNDL piece? If you have a four speed can you just remove that piece? Thanks James

[Twisted78SS]

I am fairly certain that I have a spare cluster in good working order, I will check tonight. It came out of my 78 C/10 auto.

I will post one way or another tomorrow.


Drew

[Captkaos]

Originally Posted by jlmerie

The oil gauge is NOT electric. My current speedo has two lights at the bottom, but the cluster in the picture appears to have a place for the second light. ......are the tach's pretty much interchangable between a four speed and an automatic if you have the PRNDL piece? If you have a four speed can you just remove that piece? Thanks James

If it isn't electric, you have a 76-77 cluster, it won't be a plug-in to your cluster.

Originally Posted by jlmerie

......are the tach's pretty much interchangable between a four speed and an automatic if you have the PRNDL piece? If you have a four speed can you just remove that piece? Thanks James

As I alluded to above, yes, ALL of them have 2 lights at the bottom. The one not in use on 2WD's is the 4WD light. They are interchangable, you either have the gear indicator or you don't.