Followed BC's instructions to the tee 2 years ago when I swapped my new mounts in and no problems whatsoever. Freakin HVAC people know how to rig big stuff to get into small places. It's all about leverage and looking far enough ahead for possibilities of what could happen and being aware of crush and pinch points. Only thing I did different was to chock the floor jack to keep it from sliding back

 

Don't trust anything in this thread- that truck cross-member is WAAAAY to clean.