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Mod | | | Forums66 Topics128,074 Posts1,055,914 Members48,429 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Feb 2013 Posts: 250 'Bolter | | 'Bolter Joined: Feb 2013 Posts: 250 | My '48 GMC originally 6Volt with positive ground has been changed to 12V with negative ground and has an aftermarket gauge cluster. Going back to an original cluster I know I can add a 6V inline resister to the gas gauge but will the change in ground from + to - be OK for the gauge? I do have a Chevy gas gauge that is from a negative ground truck that I could always substitute if the original GMC gauge won't work.
Thanks, Jim | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | GMC oil pressure guages have a higher oil pressure scale, dipper vs. full oil pressure. The guage doesn't care, just have to reverse leads, ammeter also.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Feb 2013 Posts: 250 'Bolter | | 'Bolter Joined: Feb 2013 Posts: 250 | Thanks Ed. I'm learning as I go along. I'll be using the tech tip here on Stovebolt on how to install a volt meter into the cluster in place of the ammeter. | | | | | Joined: May 2005 Posts: 1,624 Shop Shark | | Shop Shark Joined: May 2005 Posts: 1,624 | I believe he is asking about the fuel gauge, not the oil pressure. So you can reverse the leads on the fuel gauge with voltage drop device and all is ok?
Six volt guy living in a twelve volt world
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