Sunsilk is still around, though finding it may not be easy - I haven't seen it an in the branches of Boots or Superdrug that I go to for a couple of years, but you should be able to get it on line easily enough
Thta's a blast from the past, I used to use this in my schooldays years ago (lemon for greasy hair), was it reintroduced then as certainly didn't see it in the 80s 90s etc?
Last time I saw it was 2 or 3 years ago - they'd gone over to putting the stuff in upside down tubes and had different shampoos and conditioners for different hair types