That seems to confirm that the 57 PAF Vintage (MK1 alnico) was fitted to the LS50 in 1983. Maybe using up stock before switching to the MK2? The pickups in mine sound superb and don't sound at all nasally or lack bottom end in the front pickup.Another data point for the 1983 LS50
There was recently a 1984 TLC60 sold on Ebay UK which had the MK2 pickups.
https://www.ebay.co.uk/itm/145783909632