[BarryGMC]

Alrighty then let's talk about these old watsons. First. I believe that if you have a 3/4 to 1 1/2 ton truck and you use it nothing increases mileage better and decreases engine strain and wear more than these auxiliaries . All of you guys running 4 speeds know what it's like on those long not to steep hills where 3rd is to slow and your v6 is screaming and 4th is lugging to much. Or even with 3.54 gears 65 is really over revving the 6.
Now in the pics above we have a watson 39 that's the smaller one and a #42. I really like the 31 and 39 boxes for their size but they are older boxes and getting harder to find. But they fit the 3/4 ton trucks nicely and I mount them right in front of the carrier bearing crossmember. The same way I mount the little 2 speed watson 2021 boxes. That is how this 39 will be mounted in the 65 truck. The common ratios for the 39 series seem to be 2.11 -1 .75-1 direct 1-1. And 1.49-1. .83-1 and direct 1-1. This 39 m is the first ratios. I am not going to do the math but it allows you to spit the 2-3 and 3-4 shifts and gives you 25 percent overdrive. So over the next few weeks a will fab up a mount and show you the process of installing this in a v6 gmc truck. Later we will talk about the more common 40 series boxes.