chrome flake badly, coolant o-ring groove is cut into the rotorhousing, not the iron. Small exhaust port. Not useable in any 86+ engine because of coolant seal discrepancy.

chrome flake and compression surface wears moderately, most of these aren't in very good condition if they have over 100k miles. They're usually fine to reuse in a street nonturbo engine, but not for something like a modded t2 or an FD. They have the noise diffusers in the exhaust, so you can either cut them out or swap sleeves entirely. The port itself is identical. Plug timing is different from 89+, and these do not have the casting above the T plug for the knock sensors. Required 4 oil injectors for lube.

same as above, except with smooth exhaust port. Also they have an additional coolant passage where the LIM bolts up, on FC's this feeds water to the stock turbo through the LIM which has a drilled passage. To use this housing on a nonturbo engine or an FD engine you have to block off this coolant passage, usually by tapping and plugging.

chrome flakes and wears very mildly, holds up quite a bit better than 88 and back due to a change in coating. Still required 4 oil injectors for lube. Plug timing is changed, and matches the FD housings. All 89+ housings have the holes for knock sensors above the T plug. The NA housings have the exhaust diffuser issue that must be addressed. The NA housings do not have the coolant passage at the LIM.

same as above but has smooth port exhaust and the coolant passage at the LIM.

went to a better internal coating for slightly less wear, also required less lubrication, so they went from 4 oil injectors on all previous models to 2 on the FD. Smooth port exhaust sleeve, same as s5 NA in all other regards.

yes, you can mix and match housings of all kinds, this is the beauty of 13B engines after 86. You can purpose build an engine for many different requirements because of this. You can do complete rotating assy swaps, change irons for different intake port configurations, or improvise out of necessity.