For the single plate, it should be a direct fit, are you using the correct half case? You want to use the one without the shifting hole. From my understanding, the new tranny is the same case, just different gears, could be wrong on that though.
"if you've got something to say, say it peacefully"
Just got the parts for a new E-maxx tranny to build myself off Towerhobbies for $48 without the plate and spur gear for the 'ol revo. A steal! Anyways, The new transmission has a different case, and the gears hav been upgraded to a steel input gear, a steel idler, and finally a plastic output. Yes, I have seen it on another thread that the old transmission mounting pattern hand the holes spaced wide, but the new has 'em space longer and thinner.