Over the summer I started noticing a noise from my 1979 K10 w/SM465 & NP205 on hot days. It would start around 35mph and would not quite till I slowed to 5 mph. Hotter days the worse it got. Sounded like a high pitch whine. Today I found the transfer case was over full and the transmission was low. Thinking back I think I first noticed the problem shortly after changing the fluid in both the tranny and Tcase to new 80W90 GL5 oil. At a minimum I believe the seals will need to be replaced in the tranny output and tcase input. Anyone know of other possible causes I should check for when I get them pulled out?