...And here's where I say any and all speakers, can sound different even if they are from the same year. Is it the cab? Maybe....this 87 cab I have is VERY different sounding than any other (I owned 3 over the years, 86-88 yrs) T75 cab, next version after the vents. I know you take the speaker out individually and that's cool; but I never play them as individuals to the cab HAS to count in my review. The mids I hear in my present T75 cab, has mids that are not that far removed from the vented versions. The Vents that I had, also had to me extended lows/highs to go with good mids. These 75s I have now, have less highs/lows than the vented versions I had, and about the same mids; maybe a touch less. But very very diffferent than the next versions, that came out in 88/89 and further yet removed from the 90s till today versions that are VERY mid scooped. I've had cabs from those eras as well, bought cheap just to use the cabs for different speakers.
This cab I have now, is a throwback small check mono input that mimics an early 70s cab...maybe they used better quality wood? If so that would explain the tonal differences. These cabs went with the first Plexi reissues in 87/88.