There were a few variants of Direct (at least 3), I was working on the second iteration. The most recent version I'd seen had 4 engines to lift the Orion and Antares, a 3 engine version was identical, just with an engine "missing" as in not installed.
I think the 2 engine version was for use in LEO, I don't think it had the dv to lob Orion into a Lunar transfer. I might bring this out of mothballs and work it up for multistage or velcro, just to for something to do.