Hi,
There are a lot of good posts about the brushes replacements. This is a good one for disassembly
forum.ih8mud.com
However, I struggled finding info about the bearings so I thought to share what I have found (mine had the rear one making noise - After 22year and 290k miles of services I figure it is good PM to replace them)
Once you have everything apart, getting to the bearings is not really that hard.
Impact drill for the pulley nut makes it a piece of cake. Front bearing comes out very easy by tapping it, and I was able to get the rear bearing out with an standard 2-jaw puller from Autozone (only trick is to engage the puller on the outside of the case)
Front Bearing:
OEM Part Number: 90099-10192
Mine had: Koyo 437 (17x52x16) mm
Rear Bearing:
OEM Part Number: 90099-10140
Mine had: NSK 398 (15x35x13) mm
I struggled finding a good source for the bearings, so I ended up ordering the Front OEM from Toyota, and Rear I found on eBay
If you have a good source please post to help others
There are a lot of good posts about the brushes replacements. This is a good one for disassembly

Alternator clean and rebuild
What's the name of this site again? Oh yeah. So I was out last weekend having fun in the mud And yeah, I knew I was going to pay for it... usually it just means a lot of time with the pressure washer. But on the way home, the dash lights up like a freaking christmas tree - once when on...

However, I struggled finding info about the bearings so I thought to share what I have found (mine had the rear one making noise - After 22year and 290k miles of services I figure it is good PM to replace them)
Once you have everything apart, getting to the bearings is not really that hard.
Impact drill for the pulley nut makes it a piece of cake. Front bearing comes out very easy by tapping it, and I was able to get the rear bearing out with an standard 2-jaw puller from Autozone (only trick is to engage the puller on the outside of the case)
Front Bearing:
OEM Part Number: 90099-10192
Mine had: Koyo 437 (17x52x16) mm
Rear Bearing:
OEM Part Number: 90099-10140
Mine had: NSK 398 (15x35x13) mm
I struggled finding a good source for the bearings, so I ended up ordering the Front OEM from Toyota, and Rear I found on eBay
If you have a good source please post to help others