Rear window leaking in Ford F-150

I have a 2001 ford f150 with a rear sliding window. This is an extended cab. Whenever it rains, there are a couple of leaks from the top of the window leaking onto the rear bench. I just purchased the truck. So do I have any repair tips? May be worn out weatherstripping? Please advise. Thanks!

Bump

The next time you know it’s going to rain, take some duct tape and seal off the top of the high center brake light. If the leak stops the seal on the high center brake light is leaking. If it still leaks take duct tape and seal the top of the rear window. If it stops the rear window seal is leaking.

Tester

I think there is a TSB on this design for a leaking high center brake light. Try doing what Tester says and it will probably confirm this to be the problem. Sadly, it is not covered under recall so expect to shell out a couple of hundred bucks for it.