My 904 pulled from a 318 question

they didn't "weld a certain amount of weight" and call it balanced. They welded a plate of steel, then they spun it maybe 200 rpm's and balanced with a "light meter". They slightly removed weight using a drill. Kind of like tuning a guitar. A lot more precise than welding a certain hunk of steel in a spot.
Well of course I naturally assumed they had a laser precise measuring process at the place you took it too and paid to have it done. I was just asking if there's any information out there that you may have heard of just like there is information for counterbalancing a flywheel or balancing one and there's information for putting the weights in the correct area for a torque converter?