I have read your present replys, trash all all the replys and read following (as well as www.allexperts.com:
1.)The transmission should be driven up to normall operating temperature
2) The vehicle should immediatly be raised on drivers front side and drainplug removed, thus draining only a portion of the fluid into a very clean drain pan, collect sample of oil in a very clean oil sample bottle from your local Catterpillar equipment dealer.
3.) Spend the 10-20 bucks to have an exaustive oil analysis done on the sample.
4.) Take report to the best Volvo repair man in your local and find out from him about what may be the problem.
Notes: Use only the fluid that the trans has been using. To change to even a different brand would compromise the existing wear patterns already established in the trans.
NEVER USE SYNTHETIC OILS OF ANY TYPE in the trans.-as per every Volvo transmission professional I have ever spoke to.

As you described it may be time to consider a major rebuild, good time to consider having your half axles, tierods, struts, upper strut bushings, lower a-arms, unreachable trans & power steering plumbing.