Themes can go both ways - they are great to get the creative juices flowing, but they can also limit the number of entries if it's not a common thing.
That said, I'm not against throwing in a theme every now and then. Let's see how April goes as an open contest, and we'll collect a few ideas from you all for a theme for May.
As for March entries, yes it is a little late BUT keep your eyes peeled for the APRIL entries thread that will be going up next week!!
Also, don't forget to VOTE for March ROTM! Diesel Forum - TheDieselStop.com - View Poll Results