Problems, Maintenance, and Repair (Gen 2)
Links:
https://toyota.oemdtc.com/TSB/T-SB-0138-10.pdf
http://www.stevesalt.com/toyota-0138-10-tsb-transfer-case-inner-seal-highlander-sienna-rav4-2/
(this guy loosened all tranny bolts which would take a bit more effort)
Toyota TSB 0138-10 Transfer case gear oil or transmission fluid seepage...