Gauge cluster swap

[OldSmokey87]

Im new here and at the risk of sounding stupid I have a question. I have an 87 Silverado and some of my gauges didnt work so i went to the junk yard and pulled a new cluster. and instead of pulling one from a squarebody (because that wouldve been too easy and not as complicated) i decided to get some from a 90 Silverado with those rotating "moonie gauges" but what i didnt think about until afterwards is they have an electronic speedo (i think) so does anyone know when they started the electonic speedo in a 700r4? or a way to get it to work?

 

[chengny]

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MD8 76 88 TRANSMISSION,4-SPD AUTO (THM700R4)

The 76 & 88 indicates FY & LY (first year & last year) - of that RPO number only.

Go back to the JY and pull the VSS pickup off the transmission - was it a 700r4? If you don't have any luck there, visit this site:

http://www.transmissioncenter.net/speedometer_calibration_______va.htm

They have every conversion kit and adapter known to man.

 

[RetroC10Sport]

So wait, you're going to try to run 1988-91 GMT400 gauges? In 1990 and 1991, squares got the electronic speedo.

 

[OldSmokey87]

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These gauges but if i wanted to use these id have to put an electronic speedo in my truck right?

 

[RetroC10Sport]

Yes, no GMT400 I know of came with a cable speedo.

 

[OldSmokey87]

Alright so they started the electronic speedos in 88?

 

[RetroC10Sport]

On the GMT400, correct.

 

[OldSmokey87]

Alright so I did some researching and I found a maybe solution if I get the electronic VSS from jagsthatrun.com where it just plugs straight into the transfer case can I run that to the cluster since that cluster has the DRAC in the cluster? Would the Speedo work? Again sorry if it's a stupid question

 

[chengny]

It should work, I think. The VSS pick up is basically just a reluctor ring - similar to an ABS sensor - and generates it's own AC pulse. That pulse is amplified and drives the speedometer.

 

[OldSmokey87]

Alright thanks for the help guys I'm gonna go ahead and order the stuff and try it

 

[bucket]

How are you going to mount the cluster?

 

[chengny]

How are you going to mount the cluster?

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I was wondering if anyone was going to ask that question.

 

[OldSmokey87]

I'm making a custom dash for it. The fab guy at work said he'd make me one out of some sheet metal and I'll just mark the holes and drill them and cut where I need to

 

[Green79Scottsdale]

Looking forward to seeing it mounted.