For anyone interested in how the arrangements in and around Baltimore Penn Station (as well as early photos of the opposite side tracks/platform and others displaying UNION STATION lettering), I'd strongly suggest checking out a copy of the book "Triumph VI," which gives an amazing amount of details/photos for this location and many others between Philly and Washington.
I'd expect that any vestiges of old Station Track "B" used by the Parkton locals vanished when the parking garage was constructed. Looking at the old photos in the book, the parking garage entryway that I clearly recall pre-dating the parking garage is noticeably absent as late as 1940's, and the "B" platform seems to be accessed by an understation footway, though I believe at some point this may have been replaced with a direct stairway from Charles Street.
The book does mention the 1959 installation of the gauntlet track, but despite being very good in current Amtrak details, does not seem to mention a date when taken OOS.
One other tidbit that might be of interest is that there used to be a "High Line" at Baltimore Penn, not in the Philly sense, but a higher grade line out of the station depression that went directly to the South end of the Mt. Vernon Yards (current LR/Flexiflo term). The tracks actually crossed the B&O at grade just south of North Avenue and went through the bores currently used by the Central Light Rail Line. This arrangement certainly didn't last beyond the Expressway's construction in 1959.
And in the interest of keeping the reply Amtrak related, I've heard where in one of the large service disruptions of a few years ago, tracks 2 and 3 were actually pressed into service. I seem to recall these as being more the domain of the LD trains, prior to MARC's expansion to its current service level.