Here's some info on Compaq models that might have the CP-341 or CP-342
drives which work with the Vulcan 40:

"If you want to replace the IDE hard disk in Portable II/III/286/386 you
will need to find a standard IDE unit with a type number, the hard disk
should be labeled "type x" with x being a number between 1 and 46, these
drives are typically between 20-100Mb. Modern hard disks which are
configured with individual head/sector/tracks type information wont be
usable, there is away round this though see below. Fit the drive and set the
type number using the set up disk. A typical 40Mb unit is set up as type 17
or type 22. "