It can be done from inside the cab, but if the boom is raised, that will help some. To raise the boom on any NH LX or LS machine that has working electrical system, sit in the seat while buckled and put the boom pedal in FLOAT position after turning on the ignition. Otherwise pull the tunnel cover and remove the solenoid to put the machine into float. The use another machine with forks or a chain to raise the boom to set it on the stops. On your LX 665, you do not need to tilt the cab to replace the drive disc, and if you don't have the NH cab jack kit, I recommend that you don't. I replaced one in the middle of a high school cafeteria, so I know it can be done. You just lay on your belly for most of the day. Wedge blocks under the engine bell housing to keep the rear of the engine from settling. Remove the front (of the machine) engine mount bolt. Remove all the bolts around the bell housing. Slide the hydrostatic pump assembly forward just enough to clear the drive disc and remove same. Put the new one in and reassemble if the pump splines are OK. Bob's your uncle and your done! Basically the same process for a LS 160 or 170, except for the suction tube to the gear pump on the new units needs to be removed and plugged. Adrian
