WSDL
GP 10
http://<machinename>:48620/Metadata/WCF/Full/schemas.microsoft.com.dynamics.gp.10.01.wsdl
GP 2010
http://<machinename>:48620/Metadata/WCF/Full/schemas.microsoft.com.dynamics.gp.2010.01.wsdl
GP 2013
http://<machinename>:48620/Metadata/WCF/Full/schemas.microsoft.com.dynamics.gp.2010.01wsdl
** not a typo, gp.2010 is correct
GP 2015
http://<machinename>:48620/Metadata/WCF/Full/schemas.microsoft.com.dynamics.gp.2010.01.wsdl
** not a typo, gp.2010 is correct
Service Reference
This is the URL That you use to create a Service Reference in Visual Studio
GP 2010
http://<machinename>:48620/Dynamics/GPService
GP2013
Legacy
http://<machinename>:48620/DynamicsGPWebService
Native
http://<machinename>:46820/Dynamics/GPService
GP2015
http://<machinename>:46820/Dynamics/GPService