99 Yukon downshifting

[bdaddy152]

I have a 99 yukon that seam to have a problem with the trans not down shifting. If I come to a stop at a slow roll the trans seams to downshift with out any problem. If I come to a quick stop the trans will not downshift ontill I accelarat. you here a clunk before the truck stars to move. Like a down shift. Seams to shift ok going through the gears. Any one have any ideas.

Thanks

[maxwedge]

Welcome to AF, this clunk maybe the driveshaft yoke binding in the transfer case, common issue, GM makes a special lube to correct this, the shaft comes out and the ft yoke is lubed with this grease.