If your looking @ transmissions, I would strongly recomend reading Mac Van Pelt's (Ins and outs of early ford transmissions). Vern Tardells booklet #2 ford transmission service and repair is another good resource.
After reading both books cover to cover, you will know why those ******'s are selling on ebay and know what to look for when buying one.
Look for a 78 series case from a light-duty three-speed 39-50 truck, plus a complete 42-48 ****** for the internals. The pickup case has a thicker bottom under the relief and is stronger than the pass. car case.
I wish my rebuild parts were only $500.00, but I did have to get a new cluster, and other higher priced parts. It had a rough life and now on a fresh second chance.