I'll check when I get home ... I'm pretty sure it'd be the same on a 124 as 126. Just to clarify, when you say top right, you mean when looking at the face of the plug, not the back, correct? I won't be home until after midnight, and it's a little dark/cold to do it in the parking lot at work.
It's a bit of a pain, lots of skinned knuckles. I probably should have written down the combination of wobbles/extensions I used, but it's different for each plug. You can do it with the intake in place ... I've got small hands which helped, I guess. You will need a deep drive 13mm socket for the plug. When you go to put the new plug in, start it by hand, not with the wrench ... I was able to fit my hand in there to do so but if you can't, use a bit of rubber hose over the back of the plug to snake it in there and gently start it. Then you can put the wrench concoction on to tighten it up.

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)