Were you a fan of “Late Night with David Letterman”? Have you lost hope of ever seeing vintage “Late Night” again, beyond what you still have stashed away in your pile of scratch VCR tapes? Did you think NBC would never let go of the rights after Dave dumped them when they gave Leno the Carson spot? Well, despair not. Cable network newcomer Trio has purchased rights to a batch of the old original “Daves” and adding them to their 2003 prime-time lineup. But to whet (or perhaps deaden) your appetite, they are showing 53 hours of “Late Night” starting early Thanksgiving Day. Fifty-three hours. That’s a lot of lovely beverages, Chris Elliott, Larry ‘Bud’ Melman, and toast on a stick.