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[Help] Transmission swap 4 speed 71A - RB20/RB25DET


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First of all, i know the solution might be somewhere in this forum or somewhere else on internet but i'm lost under the tons of informations.


I have a 4 speed 240z original transmission 71A in 3 parts and straight shifter. (My 240z is a serie 1, Dec 1970)

I'd like to swap it to a 5 speed transmission.


I have sourced a RB20 and a RB25DET transmission because my first plan was to do a RB26 swap but i got a bad engine so i change my plans and go for a L stroker.


My question is, can i use the 71A 4 speed bellhouse on the RB20 box (or the RB25DET box but i guess it's now too heavy for the stroker setup)

Or do i have to source a more recent L-series 5 speed transmission (71B) ?


I have access to a machine shop for any bellhouse modifications.


Thanks for your time and help.

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I don't know the answer to your question, but below are a few good posts from other sites. It appears that if you have the correct length gearbox (660mm) then it will fit, with modifications for the larger 71C bearing and relocating one of the side mounted switches.





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