Update. I received new information and have checked into this further. The service bulletin above was dated 5/1/1990 and has been superseded by TSB DL94-001 dated 10/14/94 (previously posted on page 1 of this thread). I'm not sure why TSB DL94-001 says it's only for vehicles manufactured after 8/89, but Burntboot sent me an email last night with pictures verifying that TSB DL94–001 does indeed apply to our vans. I had previously verified Toyota made no steering knuckle changes throughout the years of 4wd van production, so if it works for Burtboot, it should work for us all. For the sake of convenience I have attached a PDF of the current TSB DL94-001 to this post.
It's unfortunate that Toyota made this so confusing but hopefully the confusion is behind us. Here's a parts list for anybody doing this job:
(qty:2) 90364-30011 Bearing, Needle (goes into inner bushing bore)
(qty:2) 90381-32001 Bushing, Inner (acts more like a bearing retainer now)
(qty:2) 90381-30003 Bushing, Outer (still the same as original)
Here are some pics of the parts (provided by Burntboot) Note: the darker colored bushings closest to the camera are his old bushings.