300SD transmission problem

Hi. I had my transmission rebuilt less than a year ago - my car has about 300,000 miles on it. The car never really shifted well after that but I had learned to manually shift because the transmission had been slipping for quite awhile before I had it rebuilt. Annnyway, today it suddenly wouldn't shift out of L, whether I was in S or D, it just whined/whurred, stuck in L. Is it possible that this can be an adjustment made by the mechanic or does it sound worse than that? I don't know exactly how many miles I've driven since the rebuild but it hasn't been a lot, I have to dig the receipt ($1800) out to confirm.

Any info, suggestions before I have it towed to his shop would be appreciated. My other car isn't running right now either so things are looking pretty bleak today.

7/7/04: Update-I had the car towed to the same shop that rebuilt the transmission 2 weeks ago next Monday and they still don't have any info. These guys are the worst at returning calls and/or calling to let me know what is going on with my car. I will never take the car back to them after this. Hope to know more soon.