6 ton jackstands, propped on the lowest strong point of the car or 12 ton jackstands anywhere usually has me getting tired from holding the air tools in the air 2 feet above the ground...
I'm 5'7, 175lbs, and we're talking about a z31.
with the transmission out, i installed the flywheel with my head in the tunnel and enough room to wield a torque wrench and have sockets on my lap and a light infront of me.
they go pretty high, these ones!