Universal joints for driveshafts from the top brands like Spicer, American Axle (AAM), Neapco, Weasler, Rockford, PTI and more. The universal joints allow drive shafts to move up and down with the suspension while the shaft is moving so power can be transmitted when the drive shaft isn’t in a straight line between the transmission and drive wheels. Combination, conversion, cross-over u-joints connect mismatched driveshaft components. They can have a variety of series and snap rings needed to make the conversion. Different u-joints are identified by the measurements or "series" they are associated with. Here are the common series identifications: OUTSIDE SNAP RING SERIES: 1100, 1110, 1210, 1310, 1330, 1350, 1355, 1410, 1415, 1480, 1485, 1550, 1555 Series. INSIDE SNAP RING SERIES: 1000, 2R, 3R Series, 7260, 7290, 5380. COMMERCIAL VEHICLE SERIES: 1610, 1710, 1760, 1810, 1880, SPL90/100, SPL140, SPL170, SPL250, SPL350.