Hello, 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.