DD> When the last partition (the Type B) is deleted, ALL the options in
 DD> FDISK is greyed out. "Create partition" and "Install Boot Manager"
 DD> is not an available option.

In which case:
        þ Exit FDISK, saving your changes of course;
        þ Immediately reboot from the installation floppies;
        þ Exit to the command line with F3 at the earliest opportunity;
        þ Run FDISK /QUERY capturing its output to file;
        þ Run PARTLIST capturing its output to file;
        þ Post both outputs here.

I'm interested to know how this type 0B partition is reincarnating itself
after FDISK has claimed to have deleted it.  So the raw contents of your
partition table, as reported by PARTLIST, and the way that your raw partition
table is interpreted, as reported by FDISK /QUERY, are of interest.

 ¯ JdeBP ®

--- FleetStreet 1.22 NR
633/260
2501/209