What was done with my son's 46 2 ton. Original 235 was replaced
with a 54 235 from a 1 ton truck.

I bought a NOS GMC gauge. The color is so slightly off and the
gauges so dimly lit that the color difference is not easily noticed.

Now the problem with the swap.

The gauge numbers are printed onto the instrument cluster glass.
So changing the gauge does not change the numbers.

You can buy a new GMC instrument panel glass that is a direct
bolt in for the Chevy glass.

So what is the problem?

The GMC glass will give you the correct oil pressure readings.
Though the GMC speedometer numbers are different then the
Chevy's so your speed will be off.

Buy a GMC speedometer or correct the oil pressure readings
in my head.

Correcting the oil pressure reading in my head seems easier then
getting a GMC speedometer because once that speedometer gets
change who knows what other problems will be added.

If I knew about be able to get the original oil pressure gauge
re-calculated I would of maybe went that way.

If I knew that no harm would of been done with the original
gauge being pegged maybe I would of went that way.

What I do definitely know is that I would of stayed with having the
original 46 engine being rebuilt due to all the little changes that have popped
up putting in the later "direct bolt in" 54 engine.
Jeffrey

Last edited by 32vld; 10/24/2017 3:20 PM.