Re: How much torque can my transmission take?
The torque rating for an automotive transmission is probably a continuous rating, or at most, its a rating based on the onset of torque that's likely with an engaging clutch or torque converter buffering the input.
The real problem with an electric motor is the rate of torque you can inadvertently put into the driveline. You're going to set that in your controller, provided you have a parameter for it. If you dump 160 ft/lbs onto your transmission input shaft at zero RPM within a few milliseconds, its very likely going exceed both the maximum torque rating of the unit, and its strength. If not the transmission, then something else, like the coupler or CV joints.
Slow that down to a rate of, say, 250 amps/second, and the transmission (and the drive axles) will no doubt last longer. That's what you're going to want to look after and experiment with.
Its also a good reason to keep the clutch in a high-powered application. It will damp the onset of torque from the electric motor, and should be the thing that lets go first. Think of it as a fuse on the drive train...