I've got a regular cab 97 K1500 with about 90K miles. Runs great! Every once in a while I'll notice my gear selector light is off, no tach, and nospeedo (all other gauges work) then service engine light comes on. The tach, speedo, and indicator light usually come back on the same day, but service engine light stays on for about 2 more...then goes off. Difficult to get a reading from AutoZone since it seems to be hit-n-miss, but got lucky last week. AutoZone man said 5 tranny codes came up, but didn't share them with me. Tranny does feel like it slips when light, speedo, and tach are dead, but feels fine when they come back on. 4X4 works great! It has been really cold lately and truck stays out in it 24/7. I'm baffled!! Any ideas?!?!?!?