Both will fit to the K20A or K20A2 engine directly. Regarding axles you have to check. You are right, the Honda transmissions are the weak link of that when power level increases or shift times go down. I am not sure if there is any difference between Y2M2, NPR3, RBC3, NPC3, X2M5 trannies. Maybe you check out this very helpful sub forum here: (1) diy|faq ☆★☆★☆★☆★ diy|faq ★☆★☆★☆★☆ diy|faq | Honda / Acura K20a K24a Engine ForumI am not sure if EP3R, FD2R etc gearboxes are a direct fit, and if any were better regarded as I know these gearboxes have some synchro issues?