Ian, I hope this helps. I just ran out in the rain to look at those hoses on my '93 940 (You owe big time!) I'd never looked closely at the vacuum set up on my car. Here is what it looks like:

1. There is a T right at the bottom of the vacuum pump. One side of the T has a small, hard tube which goes up around the strut tower and into the cabin just as you describe.

2. The other side of this T has a similar small, hard, tube which runs up to the vacuum servo at the accelerator spool. At the servo the tube connects with a rubber 90 degree connector.

3. There are 2 soft rubber tubes which go from the top of the vacuum pump to the bottom of the pump. One seems to connect back into a nipple there (can't see it clearly). The other goes to a white T on the bottom of the pump and connects at the side branch of this T. The bottom of the white T points straight down and is left open.

I wish I had a digital camera again! Maybe this info will help. My cruise control work great. The only failure was when I knocked the rubber connector off while putting in a new heater hose and valve.