trans bangs when hot

i have a 2000 buick century runs great i am a mechanic but not good with trans issues so any way when the tranny gets hot over an hour of driving it bangs through the gears fluid is clean good color 11500 miles mostly highway any suggestions? or just replace the trans

Was that 11500 miles or over 100K miles?

PCS solenoid issue. Refer to the thread below located at Buick Tips & Maintenance:

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=899929)

115000 miles but any way do you think i will have trouble replacing it myself i havent opened a trans since trade school