Can anyone clear up the record for good on the history of the transmissions that were put into the 850. Volvo tells me one thing, and an independent specialist another.

Is it true that an Aisin-Warner box went into the earliest models, and that it was replaced by a Borg-Warner?

(If it is true...)

What were the reasons for change/failures? What are the model designations of the two different trannies? Can a later model tranny be put into the earlier model-year cars?

Answers to any of these questions would be appreciated, as I am currently email corresponding with someone looking at big tranny costs who needs the issue clarified.