IIRC, the AA truck with a Warford or a specially constructed Mitchell set up on the intermediate shaft yields an AA speed comfortably between 55 and 60. Similar certainly to the Model A automobile without an overdrive.
There is a mitchell unit made to directly replace the intermediate shaft on the AA truck.
The mitchell units were like $1400 - but were basically "plug & play" with Mitchell giving you all the necessary components - including the U-joints necessary to make it happen.
Warfords tend to go in the price range of $600 to $850 (I think I sold mine to the buyer of the AA chassis I sold for $675) and I had already solved the problems of the U-joint transformations. You need to have TWO U-joints adapted to the Warford on one side (6 point spline) and the AA axle on the other (like an 11 point spline -forget exactly what it is - but new parts in both conventions are available infrequently from Dana/Spicer who make these things on "as stock required" basis.)
The thing about the Dual high AND the AA Warford is that both were derived from the Model A 3 speed transmission and is adapted to that AND the Model AA truck worm gear rear end directly. When Ford "re-engineered" the AA truck to include Borg-Warner 4 speed and the AA bevel gear rear, Ford didn't at first make the parts 'back-fit-able." Only later during the years of the Ford "Green Book" (Chassis Interchange & parts) were cross connection and backfit possibilities identified.
I was fortunate on the two U-Joints. Tam (of Tam's Model A) helped me get the first "transition" U-joint. Finding that worked, it became the model for me to examine ALL the U-Joints I could find at Amherst - until I found parts of one and parts of another that I could make up into the second unit (in their size range, the parts are all interchangeable based on the cross - the yokes vary only in the details of the spline.)
Hope this helps. I think I know where you're going.
Joe K
