I was wrong, it's a water separator apparently. There is a photo of it in this thread. I guess there must be an indicator light or something as it has a 2 conductor plug.
There is a electric pump attached to the frame on the Canadian '86 HJ60. It looks OEM and has the Toyota style connectors. The power is routed through the body (not the frame) and I'm trying to find the where it runs as well. It's not in the wiring diagrams.
The Toyota Land Cruiser 'Heavy Duty '84-'90 ? Doesn't match the colours on the Canadian '86 HJ60, not all of them anyways. I bough a Haynes manual and it's worse.