|I grabbed this from the "Noble" article at|
Wookieepedia. They don't credit the artist, but
it seems to be Gonzalo Flores, according to the
signature. If he wants me to take it down, I will.
2D = 7+
2.5D = 9+
3D = 10+
4D = 12+
5D = 15+ (figured as stat of 7 with a DM+3, or a target of 10, to get to about the same odds as 12+)
Note that these don't convert very perfectly to the difficulty levels of other Traveller editions, but then they don't really need to. The point is to get in the same ballpark, not necessarily to hit the exact same odds.
My current thinking is that T4 "Difficult" should be MT "Difficult" with an automatic DM+2, T4 "Formidable" and "Staggering" should both convert to MT "Difficult" (I could give them DMs of +1 or -1 to match the odds exactly, but that gets a bit fiddly), and T4 "Impossible" should be MT "Formidable". As an aside, that should also make T5 difficulties of 6D or higher equivalent to MT "Impossible".
I am assuming the use of the MgT stat modifiers. I haven't decided whether to use those, the original MT ones, or the ones in a set of house rules for MT I found online, where the modifier = (stat/3)-2 rounded up, or a version where the modifier is (stat/3)-1 rounded down. I'm kinda leaning toward that last one.
One of the issues involved with conversion is that I can't just take the given difficulty and port it over directly. Some of the T4 tasks rely on two attributes, which distort the probabilities since attributes are around three to five times more potent in T4 (and also TNE and T5, though that's not really relevant here) than they are in most other editions. So, a T4 task which relies on two attributes would have a target of around 14 or less on average (since the average attribute is a 7), while in MT by the book it would be an average of DM+2. A Routine task would have a 100% chance of succeeding in T4 (2D vs. a target of 14 or less), while it would have an 83% chance in MT (base target 7+, DM+2 = final target 5+ = 83%). So, instead what I need to do is check each task, figure its base odds with average stats and skill-0 if necessary, and convert it from there.
Edit to add: I want to include a link to this article, which is kept at the Internet Archive Wayback Machine.