It goes something like, the ST141/RT142 corona diffs are a borg warner unit not dissimilar to a KE70 borg warner diff. I have heard that these two are interchangeable. Adding to this, AE86 and KE70 diffs can be interchanged.
I do not understand the oxymoron that is locked lsd but I am quite sure no lsd is available for this borgwarner diff.
Short answer: don't bother, not worth it. it will fit.
