click 'Show' at
"Chevrolet Trucks (All Models Not Listed Below)", and download the '61 PDF to learn a lot about your truck - won't specify maker of trans, but unlikely you have a Saginaw unless someone replaced the original, the Saginaw [all syncro] started about 1967
yes, the speedo head could be gummed up or broken, more likely than the drive gear being gone in the trans, but that can be checked by unhooking the cable at the speedo and driving it while feeling if the cable turns
Bill
