It literally slips over the smooth end of the bolt. It's about one inch long. Here is a photo of our display engine showing where the hose would be if it was in place.
The hose on our FJ80 feels like the hose's outside diameter is roughly twice the outside diameter of the bolt shaft and it's a...
There is one on the museum's FJ80. I can't really see it but I can feel it. It's a short piece of hose slipped onto the end of the bolt. I am not going to attempt to remove it to measure it since it's not my truck. We have a display 3FE but the hose is missing from the bolt.
NEWS FLASH!
It IS a rubber hose. I just looked at our FJ80. The tip of the screw is not threaded and that hose is pushed on like an end cap. It appears that it positions the 16381C adjusting bar.
My 1990-dated microfiche shows 90445-11054. That part is discontinued. 90445 prefix parts are all "hoses" so this is probably not the correct number and it's been mis-identified for over 30 years.
NOTE: See post below for additional information.
I'm not so sure you did. If you grabbed that number from toyodiy or similar it may be a catalog error. That number shows up on the toyodiy illustration for alternator mounting and it is not correct. I have real Toyota catalog microfiche in my desk at the museum and I will examine those tomorrow.