The fact that you're asking such a question when the answer is 'full' in front should worry you more than it worries me, but, as my words in this post:
https://www.volvoforums.org.uk/showthread.php?t=310329
If you've a good 'un, you've done well. The Achilles Heel of these systems is the stepper motor. I used to repair these but these days only really want to do my own.
At worst, these are a great base for putting in £3-400 of later kit. "Classicswede' is the pro on here, and he'll better advise on which of those to go with. Else, follow my threads, and you might get lucky sorting the factory-fit.
Most don't, but if you've got the will to take this thru' to the finish, you've stumbled-on a great car. But... if it's auto, flush that box NOW!