Finally got around to installing the PST carbon fiber driveshaft.
Much lighter than stock, and smoother shifts since it's one-piece and the rubber-mounted center support of the OEM two-piece is eliminated.
Slight hum at 85-90mph, so might try to rotate 180º on diff flange.
OEM driveshaft weighed 21.5lbs, carbon driveshaft weighed 14.4lbs. Over 30% weight saving!