Where is the brake switch on a 1991 Nissan 240SX?
Normally it is behind the brake pad...feel around there it should be there.
Yes the ecu will work. First disconnect the battery and connect the new one then reconnect the batter. Start up the 240sx and it should work it not it needs to be diagnoste goggle 1990 240sx ECU CODES FOLLOW THE STEPS AND THAT SHOULD WORK I know cause I'm using a 1992 ECU FROM Nissan Stanza. I was told it's alittle advanced on the horse power side and idle moves quicker.
Where can you find an engine coolant overflow container that is not messed up for a 1991 Nissan 240SX?
You can't. I have seen probably 50+ of them, and every one is dry rotted on the front left. You will have to purchase an aftermarket overflow. Here are some links: http://www.horsepowerfreaks.com/performanceparts/Nissan/240SX/Cooling/Coolant_Overflow_Tanks http://www.prostreetonline.com/buy/weapon_r_coolant_overflow_tank/nissan/ Voodoo Street