I think you were right in the first place Basstong. If you look real closely at your machine heads, you will see that they are the right match for the B3. It's confusing I know, I thought that the B3 would be ok for my Mexican Fender Deluxe J Bass but after a close comparison I noticed a difference, being a curve at the end of the back plate on the machine heads. Your back plates look similar but the ends have no curve. Therefore, your Japanese model should fit with the B3.
The B7 x-tender has a curve and will fit should fit the Mexican J Bass.
Check it yourself to be happy.
Have a good one,
John.