But if it bothers you (it does us a little), you can purchase green bulb covers from any vendor that carries aftermarket gauges. Simply remove the two screws at the rear of the Rally-Pac for each gauge, slide out the gauge, pop out the bulb and socket assembly from the rear of the gauge, then slide a bulb cover over the bulb. You can also use a green permanent marker to color the bulbs (shown here) if you can't find the correct-size bulb covers for the low-profile '66 model.
Rally-Pac Perplexity
Reproducing a vintage Mustang part is never easy. Even if it's a single stamping of a metal part, hundreds of hours are spent checking the stamping for accuracy, thickness, quality, and so on. Now take a look at the Rally-Pac we installed and the dozens of parts it took to create (that's just one model; there are several when you include different gauge faces and colors) and you can imagine what an undertaking this project must have been for Scott Drake. We talked with the folks there about this latest reproduction part to find out what they had to go through to get it engineered, built, and to market so enthusiasts could once again enjoy the look and style of the Mustang's Rally-Pac option.
From our conversation with Scott Drake employees, the Rally-Pac was one of the most difficult reproductions the company has undertaken. Starting with designing and manufacturing all-new tooling to produce the pressure zinc die-cast housing, Scott Drake spent well over a year perfecting its new Rally-Pac. Nordskog didn't just provide an existing gauge for the Rally-Pac, it had to redesign its own products to work the way Scott Drake wanted them to.
For owners of '64 1/2 Mustangs and '65 models with the standard (non-GT or Decor Interior Group) instrument panel, CJ Pony Parts also offers the early, or low-profile, version of the Rally-Pac.
Unfortunately, Scott Drake had to relent on wiring the tach under the dash like the original. With the proliferation of in-distributor electronic-ignition devices, Scott Drake and Nordskog couldn't get an air-core tach to work properly. So the decision was made to run the single wire to the coil. I think we can live with that.
At the time of this writing, Scott Drake was working on a restomod version of the Rally-Pac that features a cool, bare-aluminum-look housing. Requests for a white-face version of the Rally-Pac haven't fallen on deaf ears and are being investigated. We were also told the company might offer the Rally-Pac in several popular interior colors or at least with some kind of paint-mask kit for those who want their Rally-Pac to match the interior. Last, Scott Drake employees told us to be on the lookout for a '66 five-dial-cluster conversion kit that will change the gauges to a more modern backlighting (like the new Rally-Pac that's much easier to read at night) but will look original. We're all for that!
10 Once you've gotten the wire through the firewall, it has to be routed to the ignition coil. We routed the wire along the intake at the valve-cover edge right along with the A/C clutch wire. The wire is black, so it conceals easily. If you want to take it a step further, cut the electrical tape off the gauge-feed harness on the engine and rewrap it with the tachometer wire included. | 
11 Once you reach the coil, the ring terminal is slipped over the negative-side coil terminal, marked "DIST" on the yellow top coil shown here. Aftermarket coils have a "-" that indicates the negative side of the coil. We used a small nut to retain the wire, then reinstalled the distributor wire over it. | 
12 As you can see, with a bit of housekeeping the tachometer wire can be hidden. This wire is the only deviation from the original design (that picked up its tach signal in line with the ignition switch under the dash). |
13 With the air-filter assembly back on, the wire looks totally hidden. Unless someone with knowledge of a Mustang's ignition circuit looks carefully, no one will know there's one extra black wire under the hood. | 
14 Back inside the car, route the underdash harness, tach signal wire, and ignition feed wire to a common location at the base of the steering column. | 
15 It's time to mount the Rally-Pac to the steering-column tube. Carefully place the Rally-Pac on the steering column and bend the wire harness to mimic the L shape on the driver side of the Rally-Pac mounting bracket. Start the retaining bolts for the Rally-Pac bracket on this side first, ensuring the wire harness is within the L of the bracket. |
16 Once the Rally-Pac is secured to the steering column, the wire-harness guide channel can be installed. One end of the channel simply slides into place behind the L of the Rally-Pac mounting bracket. The opposite end has to be secured to the steering column with the supplied Phillips head screw. Depending upon the location of the bracket, you might have to lower the steering column to get a drill bit into the right place. If you're uncomfortable drilling into a curved surface, you can always use double-sided foam tape to secure the end of the wire channel. | 
17 Finally, connect the Rally-Pac harness to the underdash harness, tach feed wire, and ignition switch wire per the instructions. Everything is color-coded, green to green, and so on, but there is one illumination wire that has a black end instead of a red one. Double-check the actual wire color, not the colored end, and you'll be fine. | 
18 The completed installation looks like the car came with it 39 years ago! The last things to do are fire up the car and check the operation of the tach, set the clock, and check the gauge illumination. For those who have never had a Rally-Pac, the white illumination is correct on the low-profile models. |