I finally got around to replacing the seals in my power steering unit on my 1991 LS400 with 180,000 miles on it.
The kit runs $24 from discounttoyotaparts.com,
It includes all seals and "O" rings in the unit. Level of difficulty is not too bad, took about 6 hours start to finish, but when I do my 1990 I think I will get it done in under 4 hours since I now know how to go about it. The hardest part was removal of the pump, since it is hard to see the bolts. There are 4 bolts holding it on2 from the front and 2 on the side at 90 degree angles to the first 2. In order to get to the front 2 you have to remove the pump pully and this requires a small gear puller.
Every seal and "O" ring was very hard and brittle, no wonder it was leaking!
If you have enough mechanical ability to remove the pump, you should be able to do the seal replacement yourself. The mechanical parts of the pump and bearing looked great even after 185,000 miles.
Best of luck: Bob