Helping a friend do his TB/WP on his '99 and there seems to have been a gasket between the block and neck. The Flyin' Miata kit only has an o-ring for this location. Since they are closed now, can anyone confirm if there should only be an o-ring at this location, or should there also be a gasket? Also, we have two thermostat gaskets, do I need to use both?
I just looked at my factory manual for an NA Miata. It shows one gasket for the thermostat and only an O-ring for the neck to block seal. I believe (not 100% sure) that all the ancillaries for a 1.6 NA are the same as NA and NB 1.8s.
Okay, that backs up my research, that is limited mainly to my '97 FSM and a '96 FSM on CD. That part of the engine seems unchanged, and though a few ancillary parts will need a tap run through, and new bolts purchased (DPO substituted a few that were overly long, which did damage upon removal), I'd like to get things as buttoned as possible tomorrow morning.
Perhaps the gasket was in place to make up for a slightly too thick o-ring.
If the o-ring is too large in cross-section, and one tightens the bolts so that the casting is flush with the block, there is too much pressure on the mounting ears of the casting. In that case, the mounting ears break off. Ask me how I know 
. So check that new o-ring!
For a NA 1.8 (1994) only an o-ring between neck and the block.
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