Good points Ted. I've found that it never hurts to use some alignment dowles whenever possible .

Make sure you get ALL the bolts off first , then get some 2" to 6" bolts with matching threads and the heads cut off.

They'll let you know right off if your alignment is close.

Just finished reduilding a Massey diesel engine . Though it has a normal rubber seal at the torque converter / transmission, the primarary oil seal is the flange on the rear of the torque converter that mates into a babbit on the hydraulic pump on the front of the transmission---very close tolerances and metal to metal --- and if those are not perfectly aligned , you're not going to get it apart or back together without ruining something