Speedometer stopped working after working sporadically and jumping all over the place. Looks like the wiring at the plug which attaches to the pumpkin on the rear diff is the problem. Cracked wiring entering the plug/connector. I'm off to the dealer tomorrow to pick up some other small parts and was wondering if anyone knows if the plug/wiring is serviceable. If so, anybody have a part number handy as I can't find one.
If not serviceable what's the best way to repair the wiring and connector.

I just fixed this with a new wiring harness to the sensor. It was surprisingly cheap at Borton Volvo. Just disconnect the connector at the sealed box inside the left rear trunk well (remove the carpet for better access), feed the new wiring through the trunk hole and secure the rubber grommet, then connect to the sensor. Make sure you route it through the right spots to keep it from chaffing. Took about an hour. To open the sealed box (sealed to prevent odometer tampering), just cut off the little hinges on the side with a knife. Re-secure with zip ties.
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See the 700/900 "FAQ" at the menu bar top screen left side.

Not sure: I am away from my reference materials.
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See the 700/900 "FAQ" at the menu bar top screen left side.

Not sure I've got the correct part number but I was down at the dealer on Friday and ordered #3523813 (electric cable). It was pretty darn cheap at $3.16 with my 15% discount! Hoping to pick it up during the week.

That sounds TOO cheap: I think mine was around $20 from Borton. Make sure it's the correct part. On the parts diagram, it is the two wire harness from the sensor, up through the body hole, to the connector in the left trunk recess. About five feet long.
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See the 700/900 "FAQ" at the menu bar top screen left side.

I agree about it being way to cheap. Told the parts guy at Stamford Volvo you can't hardly even buy a cup of coffee for that price but he seemed confident it was correct. I've got a 945 wagon and can't believe anything on that car is $3 and change! Picking up the part tomorrow so I'll see.