the te71 corolla with the 1600cc 2t or 2tgeu have a very similar diff to the ae86. this is what the person was sayin.
you can unbolt one and swap it for the other.
same T series 6.7" head. some ae86 have a longer stud at the bottom of head but it can be changed to suit.
the jdm te71 GT or levin and trueno with the disk brake T series diff have same axles as the early ae86. later ae86 have fatter T series axles. the diff housing as far as i know are same. drum brake axles have smaller bearing and not interchangeable.
calipers are different... different way the calipers slide... not sure of correct names... but ae86 have the two pins and rubber boot over em for the caliper to slide.. sim to ae82/ae82 type. whereas te71 calipers slide with plates.
the driveshaft for the 6.7" diff are shorter than a ke/ae70 U or S series diff and have larger uni's. the bigger diff head are obviously longer on the T so the driveshaft are therefore shorter.
the ma45 mk1 celica/supra have a disk brake diff similar to te71 but a bit wider... mounts, axles etc are wider but axles can be shortened to fit a te71 housing.. cut like 7mm off the splines
disk is 1" bigger tho and caliper is taller to fit.
you can bolt a te71 or ae86 diff into a ke70 but handbrake cables will need changing to suit and consider the driveshaft. i believe the S series 6.38" diff can interchange driveshaft to the T but U series 6" diff has a smaller locating ring and will wobble all over da place.