Sorry for reviving this thread. I think it's better to revive than to post a new one.

Has anyone been able to confirm if the RX8 trans guts can be swapped with NB Miata trans ones? Better yet, has anyone done this? I've been seaching for days and haven't found a confirmation, just "might"and "should" work statements.

I'm really interested in swaping the 4th gear. However, I believe the best approach is to swap all the guts.

 

Why not swap out the complete trans? It would be easier.

 

I think ít's not possible due to housing differences between both trans, according to the information posted in the following thread by Jason Saini.

https://www.rx8club.com/series-ii-technical-trouble-shooting-160/2009-rx-8-transmission-gear-chart-discussion-135710/

Therefore the only possibility is to swap internals.

 

Anyone?

Jason Saini, is it possible for you to confirm if the guts of both trans are the same?

 

Found out some "interesting info"....

I was wondering why the P66M 6 Speed Manual Transmission Assembly on the 09's are a different Part Number between the US (P6Y1-03-000) and Rest of World or RHD (P611-03-000).

Turns out the 3-4 ratio's (Gears) used on the RHD RX-8 are not the same as LHD US S2 RX-8.
After I did a complete part number cross check/comparison it revealed the differences.

By Part Number the US uses the same as NC Miata, therefore same ratio's.(P610-17-303A and P610-17-305).

But the RHD (General, Australian, Japan, Europe) has it's own 3-4 gears, sorry still working on ratio #. (P611-17-303A and P611-17-305)