No. Early isn't defined as just the ball and trunnion units. Early is 62-67 and late is 68 and up. Your 66 will be a 18 spline input shaft and have the small 1.55" pilot hub.
I'm told their is a better selection of tq converters for the 27-spline... is it possibel to convert the input shaft or am I better on getting a newew 904 for my build?