After going thru a new timing chain install on my 1989 , I found that a few FAQ's on the web have wrong part numbers for the oil seals required on a SOHC 240SX.....one FAQ had only one wrong number and the other had the seal for a DOHC.....Hey not to put anybody down, I just want to share the right info and save you some hassle.....
Oil seal-------- 150661S710
Oil seal-------- 150661S701
Nobody caught up to this but the friendly lady at my local Nissan parts dept. she squared me away and got the right parts for me....Those are the right seals for the SOHC and yes you will need
two of them.....