Hi there,
I believe the rear upright bracket needs to be 10mm as I made the mistake of drilling 12mm holes and then filling them up and re-drilling them
, unless you want to drill out your bushes to 12mm. (which I believe can be a bugger)
. Also (I know this because I measuered them today) the bottom upright holes on the MX5 are 14mm.. 12mm bolts will have too much play.
Regards Johno...