Yes your best bet is transplanting a working transaxle, will need to do some fabrication, if you can find a geared transaxle that would be the best, the MTD vari drive the hardest, the way to tell the veri drive has a belt from engine to transaxle and another belt and pulley on top of it.
Geared will have just one belt to top of or side of transaxle.
If you will list the model # and who made it (i.e. Craftsman, Husqvarna, John Deere etc.) we can tell you what it has in it.