Tough to say. His autograph has changed over the years, the 'B' has changed specifically, he generally doesn't attached the back of the letter to this rest of the B like he does in this instance anymore. And he has dropped adding his number to the autograph. Other than that, which is just a developmental change over the course of time, I would err on the side that this is real.
Imo, this is not authentic.
I agree with James. Looks like a forgery. Letter structure and size is wrong
The B and the flat T look off, even from early examples.