The Dual Range Hydra-Matic can be a mechanic's nightmare to rebuild unless you have a shop full of special tools and lots of experience. Engines and transmissions were mated at the factory with very close runout tolerances, and unless the engine block, bell housing, and transmission stayed together, it was prone to failure due to misalignment. Offset alignment dowel pins were available back then to correct for runout errors if an engine block and transmission had to be force-matched during field repairs.
Jerry
