I never understood what was meant by a *7260" or a "1350" or a 7290 or whatever other number is assigned to a yoke/ u joint
7260 and 7290 are reference numbers, but not part numbers, for the smaller and larger cross and roller universal joints commonly used in most Chrysler passenger cars and light trucks from the late 1950s into the 1990s. These were made by the Chrysler Detroit Axle Plant, as well as propeller shafts (aka drive shafts), axle shafts, rear axle assemblies, yokes, etc. The plant operated from 1917 (under Dodge Brothers until 1928) into 2010 on Eldon Avenue in Detroit, Michigan.
Other series are essentially based on Spicer references and include 1110, 1310, 1350, and 1410 series. The 1330 series was used in Chrysler and Imperial vehicles with constant velocity joints and as a single joint in 66-67 GTX and R/T. The 1350 and 1410 series were used in some larger truck applications. The 13xx series is used in other brands too.
The 7260 universal joints have a 2.125" yoke inner dimension with a 1.078" cap diameter. The 7290 universal joint has a 2.625" yoke inner dimension with a 1.125" cap diameter. The 1330 universal joint has a 2.781" yoke inner dimension with a 1.125" cap diameter. The 7260 and 7290 joints use inside snap rings instead of the outside snap rings used by the 1330 universal joint.
If you ever noticed the word "DETROIT" on a drive shaft yoke or universal joint, it is referring to the Chrysler Detroit Axle Plant, where it was made.
FYI...