Some more history behind this train:
The predecessor to this train was the New Delhi-Madras 'Southern express' introduced on April 1st, 1964. This was a faster train than the existing Grand trunk express and used to run bi-weekly initially. By October 1st, 1964, it started running 5 days a week, and for the remaining 2 days, a fully air-conditioned express used to run in a somewhat faster schedule. This arrangement continued for a while.
Sometime after 1966, the train was renamed to...
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'Dakshin' express. This lead to a lot of protests from Madras against the imposition of the Hindi name. To resolve the issue, a few changes were carried out.
1. The GT and the Southern (Dakshin) express swapped schedules. The GT, which was a daily train until then, now started running as the '5 days all classes' + '2 days fully air-conditioned' express between Madras and New Delhi on a faster schedule, while the Dakshin took up the older, slower GT schedule.
2. The Dakshin was diverted to Hyderabad, with slip coaches from Madras connecting to it at Kazipet ( 51/52 MAS-KZJ express). In due time, the Madras link was replaced with a link to Visakhapatnam.