This is the 'Pittsburgh Radio Tape', thus called because it is said to have been broadcasted in 1967 by a Pittsburgh radio station.
Paul Cable lists it in his book "Bob Dylan - His Unreleased Recordings" as being a 99,9% put-on; Alan Frazer in "Searching For A Gem" calls it a hoax:
http://www.searchingforagem.com/Starlight/BobUnrelD.htm (see Death Letter Blues)

If so, one must recognize its quality :
Supposed to have been recorded in Aug 62 in NYC, at Gil Turner’s Home, the voice is perfect, as are the guitar playing, the sound quality -quite similar to what is to be expected (that is: not good but very listenable)-, and even the fluttering of the tape in the last songs, as if the batteries were slowly dying...

And what if it was not a fake ? 
"I Can't Think For You, You'll Have to Decide..."

Anyway, this deserves room in a Dylan collection...  

I slowed it down a bit (pitch -1,60800) as the original was running really fast, but made no other changes whatsoever.