The SN65LVDS31PWRG4: Each of the four drivers handles 400 Mbps, which translates to a 200 MHz fundamental frequency in the differential pair. At that rate, FR-4 trace length between driver and receiver should stay under about 12–18 inches before signal degradation forces a repeater or cable equalizer. The LVDS swing (typically 350 mV differential) keeps EMI low, but the 100Ω termination resistor at the receiver end is mandatory — without it, reflections eat into the eye opening at 400 Mbps. The driver itself is rated for the standard LVDS output levels and can drive a 100Ω differential load per the protocol spec.
This is a standard-catalog part, not a shortage or allocation line.