I have a 1999 S80 T6 that the Volvo dealer tells me needs a new transmission (the check engine light came on, message center sats "transmissin service urgent" and at about 50 mph the tach climbs as the car coasts to a stop). They say this repair will be about $3600. I've fund some used trannies for around $1000. Has anyone replaced the transmissin in an S80? Are there software issues? I've changed out engines and transmissions in the past but the dealer says this ones to tough. Also is there any chance they are wrong and something else might fix the problem (e.g. valve body, flush and change to thicker oil)?

Thanks,

Zach
1999 S80 T6 140K, 1996 960 145K.