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Gerardo Reyes' original M601. The following article appeared in the December 2006 Power Wagon Advertiser.

I had heard about them for years – a fleet of operational Power Wagons used to ferry climbers up to Orizaba volcano in Mexico. Although I travel often to Mexico, to see this for myself I would have to make a special trip, since the little town of Tlachichuca is not really on the way to anywhere. Dr. Gerardo Reyes is the owner of Servimont, a climbing lodge on the west side of Orizaba, the highest mountain in North America, outside of Alaska. From the lodge climbers are ferried up a series of steep tracks in three M601 Power Wagons to an elevation of 14,000 feet, where the climbing begins. Gerardo finds these trucks well suited to this work. At first the roads are very dusty, then turn to fine sand as you climb the ash slopes. Then comes the mud, moistened by the snows above. Not deep mud, but slick as butter. Finally the trucks climb into the snow for the final leg. 

The Reyes guest lodge and adjacent home are massive structures of timber and rock with walls three feet thick, having withstood the earthquakes of the last 150 years. His family has lived here for four generations. As you drive into the walled courtyard, the first thing you see are the glorious Dodges. As working trucks, they are all equipped and ready to go. Two of the M601’s have the original type canvas covering on the bed, and the third has a camper on it with benches inside. A WC52 awaiting an engine rebuild is parked nearby. All of the trucks are kept under cover to protect them from the cold, wet mists coming off the mountain. Off to one side is a small parts warehouse filled with ring gears, axle shafts, and everything else you need to maintain a fleet such as this. 

The M601’s were all made in 1962, when Mexico’s military took delivery of a large number of Dodges. Other models used, albeit in smaller numbers, were wooden bodied WM300 ambulances, possibly Gerstenslager M615 ambulances, and W500 troop carriers. In later years a Mexico-specific Chrysler military truck with Dana 60 axles began to replace the M601’s, and when Mexico began buying Hummers in the 1990’s the rest were sold off. But they were not sold to the public. Only sergeants, lieutenants, and captains could buy them, at a discount price. Generals and privates were out of luck. From there they gradually made it into the general population. Unlike the M601’s used in some other countries like Thailand and Greece, all of Mexico’s fleet had winches. 

Gerardo’s fleet is pretty close to stock, with original drivetrains. Two of the 251 cubic inch motors have serial numbers that match the chassis numbers, the third has a rebuild tag covering the engine number, but it is probably original as well. He has made a number of modifications to the fuel and electrical systems to enable the trucks to perform at extreme altitude. A manual air valve on the side of the Carter carb is rotated to provide more air for the highest zones. The carb floats are lowered to prevent flooding on steep grades. Carb jets are narrowed by inserting fine bits of wire until it begins stalling, then one wire is removed. Electric fuel pumps take the place of unreliable mechanical ones. Electronic ignition is also used, and oil bath filters have given way to paper and K&N models. Timing is advanced between 8 and 12 degrees. Thermostats are 160 degree models due to low boiling temperatures at altitude. These trucks undergo a lot of twisting on the mountains tracks, revealing a weakness of the M601 body style: breakage where the cowl meets the body tub. Cab mounts have rubber donuts above the floor as well as below. Likewise the express beds have been reinforced with 1 inch angle along the inside due to cracking. The Braden MU2 winches have in some cases had the rear cross member reinforced, a weak point that developed when Dodge went to the longer 251 engine and apparently tried to save space by changing from an angle to a flat strap. Although these trucks all run, they aren’t show trucks, as all the welds and cracks testify. 

“Would you like to take one for a drive up the mountain?” asked Gerardo, and of course I said yes. I picked the light green one, which is the one he has had the longest and was featured in Willie Worthy’s Four Wheeler article. It has the original wooden troop benches in the back. Although he hadn’t driven it in a month, it started right up. This truck has electronic ignition, courtesy of a modified distributor from a 225 slant 6 engine. Gerardo gave me directions out of town and up toward the mountain, and off I went. This was the first time I had driven a 251 engine as opposed to a 230, but it was hard to tell the difference given the altitude. I was climbing at first up a steady grade on a paved road toward the volcano, and 3rd gear was the best I could do. Cornfields on either side of the road soon gave way to open stands of tall pine trees. When the paved road took a left toward a village I went straight toward the mountain on a dirt track. I climbed until I found a good spot to photograph the glacier high above. On my way back down the paved road I was surprised to see a ¾ ton WC coming up the road towards me, not one of the trucks I had seen at the climbing lodge. The three men in it waved as they passed. It turns out that this truck had previously belonged to Gerardo, and was a KD ambulance. The heavy ambulance body had been removed and it was now in use hauling oats from the fields. 

Gerardo is no great fan of the 9.00-16 NDT tire, and has a number of other types in use besides these. He says the NDT is no good in mud, causes the truck to slide sideways off the track in snowy conditions, and rides too rough on the highway. He likes Michelin XZL radial tires although they aren’t so great in the snow either. Super Swampers have given him better performance, though the soft rubber edge lugs tear off easily. So when I visited him he was still considering other tires, perusing tire catalogs and dreaming about custom wheels 8 inches wide. 

Several of his trucks have modified rear axles. He has some of the early Lock-Rite electric locking differentials developed by John Zentmeyer, and hardened axle shafts made by Moser. He says the short shaft is most likely to break, especially with the diffs locked. The steep roads and heavy loads contribute to that problem also. All of these adaptations were ones he had made for his specific working conditions, and the fact that these 44 year old trucks were still doing this tough job says something about what modern trucks may be lacking. Gerardo talks fondly of the trip he made north to the first VPW rally, and of meeting Dave Butler and Gordon Maney. Maybe he will make it back for the 20th anniversary.