There is no specific version of ActiveMQ "Classic" which corresponds to JBoss A-MQ v6.3. JBoss A-MQ 6.x is based on ActiveMQ "Classic" 5.11, but it's been fairly heavily modified with bug-fixes, component upgrades, etc. over the course of several years spanning the duration of the 6.x product's life-span.
There is no specific version of ActiveMQ "Classic" which corresponds to JBoss A-MQ v6.3. JBoss A-MQ 6.x is based on ActiveMQ "Classic" 5.11, but it's been fairly heavily modified with bug-fixes, component upgrades, etc. over the course of several years spanning the duration of the 6.x product's life-span.