Yes they are but you can correct that. You can use a stand alone deisel trans controller or you can go to a full manuel valve body with a good rebuild kit. I personally have a Buick Grand National 200-4R trans in my El Camino with manuel toggle switch for the converter lock up, they are running these trans with 1000HP turbo buicks. It cost me about $800.00 for the full beef up. But back too the 4L80. Here is a site that sells all the parts to convert to a manuel valve body, also TCI sells one already built with the conversion. After looking back on my original recommendation, i should have suggested the 200-4R it's easier and cheaper and doesn't require a computer.
Zip.
http://www.transmissioncenter.net/4l80e.htm