My 1985 740 wagon was purchased new and has faithfully served our family for years. I was replacing instrument lights recently and noticed a 6x6x2 black box (presumably electronics) attached by 2 brackets under and just to the left of the steering column and just above the clutch and brake pedal. Its wire harness goes from its left side into the space just behind the radio, ashtray, fuse box. Can anyone identify the function of this part with this limited (so far) information. Is it part of Volvo's original manufacture and supports the car's systems or is it likely aftermarket electronics installed to support a mobile phone (long since removed) or for a radio replacement for the original?

If you need more info to respond, please let me know. Thanks.