Will the stock transmission be compatible with a sr20det in a 1991 Nissan 240sx 5 speed?

Yes, the stock 5-speed transmission in a 1991 Nissan 240SX can be compatible with an SR20DET engine swap, as both the SR20DET and the stock KA24DE share similar transmission mounting points. However, you may need to use an SR20DET bellhousing or an adapter to ensure proper alignment and fitment. Additionally, considering the increased power output of the SR20DET, it’s advisable to check the transmission's condition and reliability for long-term use.