RCM on vehicle hire charges

Yes as per S.no.15 under Notification 13/2017 CT rate; Service provided by Non body corporate who is not paying tax @ 12 % under FCM by way of Renting of any motor vehicle for transport of passengers, tax is required to be paid by body corporate under RCM.

So did you mean body corporate includes LLP or firm under gst act

Body Corporate is define under section 2(11) and section 2(20) of the Companies Act 2013 , so in my opinion you have apply for Advance Ruling under section 97(e) of the CGST Act 2017.

Also in Notification 13/2017 CT ( Rate) 28/6/20017 under explanation (b) of body Corporate has been given. but in my opinion still you go for Advance Ruling.

No need of so many notification.
GTA (GOODS TRANSPORT AGENCY) FALLS UNDER THE PREVIEW OF SEPERATE NOTIFICATION.SEC 9(3) OF CGST ACT AND SGST ACT STATE THAT GOVERNMENT CAN SPECIFY CATEGORIES OF SUPPLY OF GOODS AND SERVICES . THESE ARE COVERED COVERED UNDER RCM.
THERE is no seperate head under rcm.

Yes you rightly replied that Section 9(3) states that Govt can Specify................  now what you think how the govt can Specify the services on which RCM is applicable.... let you clarify that it's Notification by which govt notify the services & and the category of person whom the RCM is applicable.  So only going through provision of Act one cannot know that RCM applicability under Section 9(3). 

Thus Notification is important to get correct interpretation of LAW written. 

Notification is important for correct interpretation when there are some ambiguity but not always. Body corporate is covered under seperate Act. Now here certain category of services are chargeable under RCM.

So this "Certain categories" is not defined in Act , It is being provided in Notification.

Note : Body Corporate is also Defined Under Explanation in Notification 13/2017 CT