Unfourtantly I don't think you will be able to buy one. That was the very first part I looked for. I am trying to fab one out of sheetmetal to resemble those on big deissel trucks. keep me posted as well plz.
I have just bought my 89. Started to bring back to lifean was working on the dome lights yall probly know this. The solid black gound wire is to the headlight switch an the blk with white stripe goes to the door switch. :doh: