it honestly could have been a 10mb, I don't even remember. only thing I really do remember is thinking it was interesting how it used the floppy and second cable, and how the sound it made was used in every 90's and early 2000's tv and movie show as generic computer noise :)
You have me beat on the XT, mine was a 286, although it did replace an Apple 2e (granted both were aquired several years after they were already considered junk in the 386 era).
My first one was a Seagate ST-238R. 32 MB of pure storage, baby. For some reason I thought we still needed the two disk drives as well, but I don't remember why.
"Oh what a mess we weave when we amiss interleave!"
We'd set the interleave to, say, 4:1 (four revolutions to read all data in a track, IIRC), because the hard drive was too fast for the CPU to deal with the data... ha.