Good evening -
Yes, RHD and LHD are different, and there's variations in LHD types.
With a 940, it's an easier job if one removes the dash.
With a 960, it can be done without removing the dash (at least in Robert DIY's vids for LHD cars) but the advice I got here says it's an easier job after removing the dash.
In both cases, there's a line of 7mm self tappers along the top, sides, and base of the blend door box in front of the heater core, and they're inglorious bastards to get to, even when the dash isn't in the way.
Pic below shows the blend door box on the RH side of pic, with oval air outlet. Note line of screws near where the coloured vacuum control lines run along to the top of the blend door box.
This pic is from my last under-dash adventure in the 940T back in early 2019 to replace a failed 2-port vacuum motor, but the heater core didn't have the common decency to fail before I did that job.