I decided to change my oil today so I went down to autozone and got 5 quarts and a filter $15.11. There book showed that the right filter for a 86 22re was a s16 which is a stp brand but this filter is bigger then the 3614 one on my truck. I was wondering if anyone is running this size filter? Also there book showed that this filter was used up untill 86 then from 87 on the filter is s3614 am I missing something here I thought all the 22res from 85 to 95 were the same.Also does the s16 filter have a anti drainback valve? I looked into k&n filters and it appears that there are two different parts numbers HP-2004 is for 75-86 motors and HP-1002 is for 87-03 motors so if the motors are the same why are there different filters?