Hi Jim,
I am using a set of BH-6, with bell ends. I believe these are the same size as the Jr's, the only thing that might be different is the the stack thickness. The BH-6, stack is 1.25" and I think the Jr's are the same.
With the bell ends front to back they are.
2.20" Wide, 2.90" high and 2.80" deep.
The mounting centers are,
1.75" wide by 1.80" front to back, these are plus or minus about 0.1" as I can't get my calipers down that far...John