Abstract: A driveshaft assembly including a driveshaft having a first recess proximate a first end, and a second recess proximate a second end. The assembly also includes a first key within the first recess, a second key within the second recess, a first end housing, and a second end housing. The assembly further includes a first thrust bearing seat coaxially disposed within a first receptacle of the first end housing and including a first end, a second end, and a first length L1 measured axially between the second end and the first end, and a second thrust bearing seat coaxially disposed within a second receptacle of the second end housing and including a first end, a second end, and a second length L2 measured axially between the second end and the first end. L1 and L2 are both fixed and L2 is greater than L1.

Abstract: An embodiment of a method for drilling a borehole into an earthen formation, the method including contacting a first end housing at a first axial position with a first drive key, wherein the first end housing has a central axis, a first end, a second end opposite the first end, and a first receptacle extending axially from the first end, and wherein the first drive key is disposed within the first receptacle in the first end housing and radially disposed between the first end housing and a driveshaft. In addition, the method includes transferring torque between the first end housing and the driveshaft via the first ball during. Further, the method includes, contacting the first end housing at a second axial position with the first drive key or a second drive key after (b), wherein the second axial position is axially spaced from the first axial position.