There's no doubt about it, anyone that owns a classic truck will tell you they enjoy the nostalgic feeling they get when they drive it. It might be said an old truck's ability to make one feel young again works better than any vitamin or anti-aging cream on the market-unless, of course, it also brings back some unpleasant memories. I love my '68 GMC, but the dashboard reminds me of when I was a flat-broke 16-year-old kid driving a beat-up old heap with nothing in front of me that worked. Not only was it a drag not being aware of how things were going under the hood engine wise, but not having a speedometer made me paranoid every time I saw a cop.
Beyond a desire to have everything working on the Jimmy's dashboard I wanted to make the truck look better and offer more options than it came equipped with brand-new. All it took was a visit to the pages of LMC Truck's catalog for '67-72 Chevy and GMC trucks and I located 98 percent of what was needed to do the job. I also looked to Mothers for detailing products needed to carry out restoration processes and Eastwood for paint supplies.
Here's what we had to work...
Here's what we had to work with; a gauge cluster packed full of instruments that didn't work and one of the weirdest factory color combinations imaginable. LMC Truck's Color Bond made an easy job out of handling the color change, and installing LMC Truck's complete dash cluster meant new gauges without having to address sending unit modifications.
On a personal level, I admit I kind of liked the strange contrast GMC created by using red and green, which are complementary colors, to decorate the interior of the cab but I was after a sexy '60's high-performance look.
The easiest way to do work behind a dashboard is to get everything out of the way, and gain direct access. The original glovebox was in tatters and came out with an easy tug to tear it out, but installing the new reproduction glovebox from LMC Truck required finesse, and a little bit of good timing. By timing I mean it was best to handle installing the new AM/FM stereo and dual-cone speaker before stuffing the new glovebox in. This was also a good time to remove a rat's nest of unnecessary wiring present.
The decision to scrap the original GMC cluster was a good one. Installing LMC Truck's new dash cluster returned complete functionality to the GMC's dashboard and added a factory-style tachometer in the process. I was lucky because there are other things that will prevent gauges from working. For example, a broken speedometer can be caused by a bad speedometer cable or drive gear. Because early C10s use a mechanical oil pressure gauge there's no sending unit to go bad. The problem is going to be either a broken or disconnected feed line or a bad gauge. A faulty sending unit, a broken gauge, or a disconnected wire can cause a coolant temp gauge failure.
The best way to upgrade the sound system in a classic truck is forgo destroying the original looks of the dashboard by cutting the sheetmetal and opt for a shaft-mount style unit that slips right in the existing hole. I went for LMC Truck's dual-cone speaker because I wanted stereo separation, but I didn't want to draw any extra attention to the truck by installing visible stereo speakers in the kick panels. It must be added that the sound quality isn't quite as good with a single speaker in the center of the dash. The finishing touch that really turned up the nostalgia was installing LMC Truck's beautifully chromed glovebox door. Chroming the glovebox door was a trick us California customizers used to do back in the '60's that made it a lot easier for our girlfriends to check their makeup.
The first step was to disconnect...
The first step was to disconnect the battery, eliminating any chance of grounding a stray hot wire while working under the dashboard.
It's a bad idea to use harsh...
It's a bad idea to use harsh detergents around interior plastics. Instead we used a heavy concentration of Mother's California Gold car wash to cut through 40-plus years of grit and grime. Compressed air works best for drying things out and begins the process for color-changing the interior with Color Bond.
Removing the glovebox allows...
Removing the glovebox allows the best access when replacing the radio and speaker. Note the glovebox hinge serves as a clamp to retain the box's bottom.
In order to install the new...
In order to install the new glovebox, the heater plenum must be removed. It is not necessary to remove the front half of the heater assembly mounted under the hood on the passenger side of the firewall.
I used a scissors jack with...
I used a scissors jack with a block of wood to turn mounting (installing) the new glovebox into a one-man operation. It's best to proceed carefully as forcing the glove liner into place can tear it and cause permanent damage.
Adjusting the glovebox liner,...
Adjusting the glovebox liner, glovebox door, and door latch was accomplished by leaving the mounting screws loose and jiggling the trio of components into position then tightening the screws down snug.
To remove the dash cluster...
To remove the dash cluster all of the knobs must be removed first. Each knob is attached in a different fashion and must be removed accordingly. The choke knob unscrews by holding the flats on the choke cable shaft and turning counterclockwise.
The wiper switch knob is held...
The wiper switch knob is held tight with a tiny fillister head set screw located on the backside. Snap ring pliers work great for unscrewing the chrome collars found behind each of the knobs.
The trick to removing the...
The trick to removing the headlight switch knob (shaft) is to compress (squeeze) the button my thumb is pointing to while pulling the light switch knob out. To reinstall, the button must be squeezed again. Some jiggling might be required.
The mechanical oil pressure...
The mechanical oil pressure gauge must be disconnected before removing the dash cluster. A 5/16-inch flare-nut wrench works well for undoing the fitting without rounding the flats. The speedometer cable unscrewed by hand from the speedometer back.
The gauge wiring plug on the...
The gauge wiring plug on the gauge cluster's backside was undone by squeezing the ends. All of the Phillips head screws on the dash cluster's face were removed and then the dash cluster was lifted out the left side while jockeying it free from top and bottom snags.
Connecting the factory optional-style...
Connecting the factory optional-style tachometer in LMC Truck's reproduction dash cluster is a simple matter of plugging the included harness into the back of the dash cluster and the routing the brown feed wire to the negative side of the coil and the pink (hot) lead to the terminal marked "ign. unfused" on the fuse block located under the dashboard on the driver side.
On Delco window-type distributors,...
On Delco window-type distributors, the brown lead attaches to the negative side of the coil. On GM one-wire HEI distributors the brown lead attaches to the terminal marked "tach" on the distributor cap.
Taking special precautions...
Taking special precautions not to scratch the chrome, LMC Truck's dash cluster installed by reversing how the original came out. Next, the Phillips mounting screws were tightened into place, and the oil pressure gauge and speedometer were reconnected.
Thanks to connecting to existing...
Thanks to connecting to existing terminals, notice how uncluttered the fuse block remained after installing LMC Truck's complete dash cluster and AM/FM stereo.
Here's the dash cluster in...
Here's the dash cluster in action. The tach is at 2,000 rpm, the fuel gauge is at a little over a quarter tank, and the temp and oil gauges are reading as well.
Removing the original radio...
Removing the original radio consists of pulling the knobs off, and then undoing the nuts on the shaft mounts followed by unbolting the support bracket attached to the speaker mount. Next, the speaker is removed by unbolting it from the mounting bracket.
A test fit of LMC Truck's...
A test fit of LMC Truck's AM/FM stereo dictated the opening in this particular dash needed to be opened slightly with a file. Damage to the AM/FM's chrome face can result if a force-fit is attempted.
With stock-style knobs and...
With stock-style knobs and face it's hard to tell the difference from an original GM radio. The USB port is a hanging plug that easily tucks into the ashtray when an iPod is not in use.
The quick way to adjust the...
The quick way to adjust the radio face as flush as possible is to assemble the front, and then take up the slack on the shaft mounts from behind. Note the adjusting nuts and washers shown in this view.
Mothers' California Gold car...
Mothers' California Gold car wash works great for restoring the original appearance of the dashboard, but a good silicone and wax stripper like Eastwood's PRE should be used as the first step to color-changing the padded vinyl dash with Color Bond.
The next step to achieve an...
The next step to achieve an extremely durable finish is to spray on Color Bond's adhesion promoter and then allow it to tack-dry before applying the color coat.
Not a lot of masking is required...
Not a lot of masking is required because Color Bond dries almost immediately after being sprayed, thus the amount of overspray produced is minimal. Leaving the windshield unmasked allows plenty of light to see the surface, and is easily cleaned with PRE, a single-edged razor blade, or 0000 steel wool.