Found this on the TDR board in the classifieds.
Fiberglas & steel tractor cab to fit JD LX172, LX173, LX176, LX178, LX186, LX188. May fit others with modification. Lists for over $1500.00 new. In great shape. Part # TY16188.
can be bought new here:
www.stonehams.com/pdf/lawntrac.pdf