GST on mounting of Bus/Truck Body by job worker on chassis supplied by principle

In re V E Commercial Vehicles Limited (GST AAR Madhya Pradesh) Whether mounting of Bus/ Truck Body by the job worker on the chassis supplied by the principle for which the applicant charged fabrication charges including cost of certain material that was consumed during the process of job work would be classified as supply of service under HSN 9988? Supply towards provision of services in respect of activity of mounting/ fabrication of bodies on chassis provided by Customer should be treated as supply of bus or provision of services in respect of activity of mounting/fabrication of bus body on ...