Going by the book while driving and repairing fine vintage automobiles usually means running into the point where the manual says use Special Service Tool X-5745 to remove a bearing, or SST set 09612-10091 and a block of wood to overhaul the steering gear. Many of these tools have long since been tossed into the dumpster of discontinued parts. Lack of availability can result in fabrication of customized sockets or creatively bent wrenches. This would especially be true if you drive a 1959 Fiat 600, but not in this case. Dan Lennon is not only the proud owner of a Concours’ d’Lemons winning Fiat 600, but also the special service tool devised in Italy solely to tighten the otherwise impossible to reach cylinder head bolt behind thermostat housing. Dan carries this tool and torque wrench with the Fiat. Not all of us are lucky enough to locate these most purposeful of tools. Somewhere in the Clunkbucket Arsenal of Tools is a box end wrench bent into a 90-degree angle with open end hacked off in case of small block Mopar distributor adjustment.
I was a professional wrench-twister for about 8 years. It is a common thing for mechanics to make their own specialty tools for a variety of reasons, including those given above. Many times it was simpler and cheaper to make a tool rather than buy a factory item (which may no longer exist) or just quicker.
Every Datsun mechanic I knew had a special 10 mm box end for getting at a pesky bolt on a 510 carb base.