I discovered that the SGL and Turbo seats don't have seat heaters. As I live in almost arctic conditions, the temperatures outside during wintertime can drop to -30 degrees centigrade. A very good reason to have seat heaters. My old GL seats, the blue and the gray/black ones, have seat heaters.
My old original blue GL seats are very worn and I don't use them anymore, so I disassembled them and ripped out the seat heaters. They didn't fit straight to the SGL/Turbo seats, because the amount of seams was wrong on the parts where the seat heater would be installed. The GL seats have 4 seams whereas the SGL/Turbo seats have 5. I had to use the sewing machine.
I hope the heaters work as they should. But they should because the heater elements are all intact. And I managed to install them without breaking anything. I need to get the seats to a workshop where they can repair the upholstery, the seats are not quite as good as new. And I want to get the blue striped parts replaced with gray fabric to make the seats fit the interior color scheme. For now, I will use seat covers. I cannot replace large pieces of fabric myself because I'm not that good at tailoring.
The rails were quite rusty on the SGL headrests and the GL headrests' rails weren't rusty at all, so I took the headrests from the blue seats and swapped the fabric from the SGL headrests.
Here are some photos of the process, it's a lot of work but fortunately not so difficult. It took me three weekends to do this, but I think it's worth it.
I thought I'd show this to you guys because it was a lot of work doing it and I'm happy with the end result.
JP