One way to find out is giving the 90/91st day of travel and check out the total number of seats vacant. It will show the details. This facility is available for all classes, and all trains. but only laborious work is to choose the trains individually.
As far as 3E are concerned, they are being removed as per recent news reports since they were finding SMBs uncomfortable.
Any blogger who has more faster way of search may respond/ provide info for all bloggers knowledge enhancement. thanks