MW solid driveshafts are for use in vehicles with solid mounted rear ends where a single coupler is not long enough. These shafts are available in stocked lengths from 6" to 28". All shafts are machined out of 4340 alloy steel, micro polished, heat treated with MW's austempering process, and black oxide finished. Standard shafts in stock are 1-3/8"-16 straight key, 1-3/8"-32 involute spline, and 1-1/2"-35 involute splines. Shafts over 12" have 4 full inches of spline on each end and can be shortened up to 2" on each end. Couplers and splined shafts should not be used unless perfect alignment is assured. Critical speed calculations must be considered for these shafts. Call or contact us with your numbers to confirm the RPM critical speed value. MW can also build custom solid driveshafts to your specs with different splines upon request.