mx5 diff problems

[PorkChop]

The 1800 diff has a larger crownwheel and is physically bigger (might be a bit longer too). The 1600 and 1800 driveshafts are different, so if you fit a 1600 diff you will need 1600 driveshafts too. On MX5s, the prop must also match, but I don't know whether the prop length is the only difference and therefore not an issue on a Roadster.

Push in driveshafts will also fit bolt in diffs (at least for the 1800s, as I have this exact setup on my Torsen).