Steve Baur
Former Editor, Modified Mustangs & Fords
October 17, 2012

With the price of gasoline creeping higher and higher at every commodity trader's whim, some owners may find it increasingly difficult to fill up their classic car, or take it on that weekend getaway simply because of the poor fuel economy. Shane Struthers of Tarpon Springs, Florida, experienced this firsthand when the majority of his vacation money went toward filling up the tank in his '73 Mach 1 Mustang.

It turns out that the thirsty 302/C4 drivetrain combination isn't the most frugal of gas sippers when it's buzzing at 3,000 rpm while going down the highway at 70 mph. Do this for, oh say 1,000-plus miles like Shane did while on the Hot Rod Power Tour and you can imagine the sucking sound the debit card makes at the pump as it drains your bank account.

To remedy this situation, Struthers contacted the folks at Monster Transmission in Brooksville, Florida, to see what they could do to ease the excessive highway rpm. The solution came in the form of one of the company's AOD swap kits.

The Monster AOD is fortified with Alto clutch packs and friction plates, as well as Kolene steel plates to provide a gearbox capable of 450 hp. We documented the buildup of a similar AOD in our Feb. '11 issue, which you can obtain through our back issue department or check it out on our website. In this article, we've documented the installation of the AOD in Struther's fastback. The result, as predicted, knocked the cruise rpm down considerably, so the next time Struthers wants to make the long haul, he'll have a little more green leftover for the fun stuff.

Shane Struthers, and his father Gene, built this Mach 1 from the ground up over a year's time. At just 17 years of age, Shane has plenty of time to enjoy his Mustang in the future. Having followed the Hot Rod Power Tour in 2011, Shane dropped more than $1,000 on high-priced gasoline to make the trip. With the three-speed automatic, the Mach 1 was turning 3,000 rpm at 70 mph, and sucking the tank dry. Now with the added overdrive from Monster, Shane tells us that the Mach is now a highway cruiser turning just 1,750 rpm at 75 mph. That'll keep those butterflies closed a bit more and likely improve fuel mileage considerably.

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19 The speedometer driven gear is updated to accommodate the different gear ratio of the AOD and keep the speedometer reading accurately.