Depends, for what application. caldina st215 had a viscous coupler but some had rear torsen lsd. If both were fitted to the rear it does nothing for performance. with the open front differential it would be same as awd, matrix, rav4, rx300. Edit: would the monkey grip lsd patch this for automatic gts?Check out the 2009 Matrix New car features and it talks about it.
They were viscous couplings from 04-08 so I guess one of them would work as long as you use a trans that doesn't have a viscous coupling in the center diff, which the Celica GT4/alltrac/Caldina transmissions all do.
Personally I would rather just use a Caldina diff since they are a straightforward mechanical diff.