The back stabbers are a two part plastic unit that splits apart. The cord is trapped in the split at a certain length to provide the correct tension for the blind to work correctly. To little tension and the blinds will slide down while you drive. To much tension and the blinds will be hard to pull down and cause undo stress on everything.
I would mark the strings with masking tape folded over on itself trapping the strings just above the stabbers. This way you will have an idea. Of the correct tension.
Also if you do not want the stabbers they are not need. You can see how to remove them in the link below stating with this post and the next two after that.