I've always assumed that SLV and ASLV used the same launch pad, but when I tried to look up the old pad on Google Maps I noticed what looks like a hangar on rails a couple hundred metres south.
https://maps.google.co.uk/maps?hl=en&ll=13.665441,80.227087&spn=0.003002,0.005284I can't find many images of the SLV which show the launch pad, but the few that I have seen suggest that the pad was similar to Vandenberg's SLC-5, with the rocket integrated horizontally and the tower used to raise the rocket to vertical, support it, and then launch it. So I'm now wondering whether the hangar is in fact the old SLV pad (presumably being rolled away before the rocket is erected), with the pad slightly further north being built later, specifically for ASLV.
Does anyone know if this is correct, or anything more about these complexes?
The last time I saw the ASLV pad, it was covered in thick bushes..abandoned years ago...

SLV-3 as you mentioned, was assembled horizontally and moved to the launch pad. But, as per my knowledge, SLV-3 used a different structure for the launch.
I expect all these to be cleared in the next few months as they are planning the third launch pad at Sriharikota
I thought the SLV/ASLV launch pad was converted into the First launch Pad?
I thought the SLV/ASLV launch pad was converted into the First launch Pad?
FLP is confusingly named - it's caught me out in the past - assuming SLV and ASLV used separate pads then it is at least the fourth pad (there's a sounding rocket complex somewhere at SHAR, but I can't find it on a map).
ASLV was still flying while FLP was being built - indeed, the last ASLV launch didn't occur until after the first PSLV.
Yes, there are/were 4 different pads and 1 sounding rocket complex
According to the "Space Technology" book by Kenneth Gatland, what you show is the "Liquid booster satellite launch complex". The SLV-3 pad is more south than that. The remains of the pad might be at +13° 38' 52.44", +80° 13' 30.82".
Yes, there are/were 4 different pads and 1 sounding rocket complex
But how can you say so? Do you have some sort of reference to justify it? If yes then do reply.