Ecobox/205 FTW! I think it shouldn't matter if you have a ford driver drop 205 on the back of it. When I ordered my Titan box from NWF, they asked if it was a ford or gm/dodge 205 I was putting behind it...I think it should work for both, but may be worth a call to pick NWF's brain on it.
I say no on the Ecobox/241. You basically create only having a 3 speed case instead of a 4 speed case with a 205 (since the gears in both the ecobox and 241 are identical, it wouldn't matter which you put in low/high, you would only have the options of 1:1, 2.72:1, and 7.4:1), and added to, 7.4:1 is probably a little too low for this thing. Especially if you are rocking 39's (I believe that is the size of those Irocs from your old blazer, correct me if I'm wrong), I think you would find that being in low/low would be such a low gear that it would be pretty much unusable in many circumstances. I would much rather have the full options of 1:1, 1.96:1, 2.72:1, or 5.33:1 of the 205 route, but that's just me