These are typical Spicer universal joints from Inland Empire Driveline. On the left is a 1310 with a grease zerk and internal C-clip bearing caps. On the right is a 1330 sized for a big-block Mustang and designed for external clips. Note the absence of a grease zerk on the right because the 1330 is lifetime lubricated. Lifetime-lubricated universal joints are stronger because they're solid steel and void of internal grease passages.