I am shopping around, using car-parts.com, mostly.

It seems there are a few that the guys claim would fit my car, but some come from a V70.

The tag on the tranny is 55-50 SN.

What other transmission would fit in my car?

The shop only has one currently but it is from an 04 and is a 55-51 SN, I doubt it will fit.

Thanks!

 

The 55-50 SN was only in 01-02 Volvos so you are really stuck with those years.The ECU will not allow anything else to be used even if you could be it to fit.Sry

 

How about replacing tranny w/ a newer model like an 03 and also replacing the ECU also from an 03. Will there be complications

 

No the 03+ 55-51 SN is a 2.5t engine and is different in almost everyway. The 2001 S60,V70,V70 XC use all the same Trany.This link will give you a break down on your Transmission http://www.docstoc.com/docs/20499384/Aw55-50-sn .The only choice it seems is buying a salvage/junkyard trany im guessing $2000ish not installed or having yours rebuilt $3000-$3500 installed is a good deal on this .Dealer rebuilt $4000-$4500 installed.