The F-14A+ is the F-14B. They are literally the same jet. The designation "F-14A+" [or "F-14A(PLUS)"] was changed to F-14B in 1991 to avoid confusion.
From what ive heard in the DCS F-14 discord server (its a very nice place for finding out rare or obscure information on the tomcat. Ive been researching it for over a decade now and i still pretty regularly find out new things there), the designation change was due to a new logistics software freaking out over the A+ designation and at random sending A+ parts to A squadrons and A parts to A+ squadrons. And it ended up that it was easier to re-designate the F-14A+s to F-14Bs than to commission a new logistics software.
TMF F-14 Tomcat Super Pack v1.32
in F-14
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From what ive heard in the DCS F-14 discord server (its a very nice place for finding out rare or obscure information on the tomcat. Ive been researching it for over a decade now and i still pretty regularly find out new things there), the designation change was due to a new logistics software freaking out over the A+ designation and at random sending A+ parts to A squadrons and A parts to A+ squadrons. And it ended up that it was easier to re-designate the F-14A+s to F-14Bs than to commission a new logistics software.