The manual says they are 8mm. I had no problem getting one at local industrial fastener store although it had an Allen head (which is better as you can get a better grip on it). Any one who undoes bolts and nuts should have a metric/SAE tap and die set to chase them. You can get a complete set for about $45 on sale. Mine has both 8mm and 9 mm sizes.
- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT