As with so many things relating to a Morgan, "it depends..."

TR intake manifolds changed as the motors changed from the TR-2 through the TR-4A.  If you
have a Morgan Spares or Moss Motors catalog handy (or most any TR 2-4 parts catalog) you
can identify it visually.  If it pre-dates the TR2, 3, or 4 motors then I'm not certain what it looks like.

Fundamentally there are three manifolds with the following distinctions:

TR2 through early TR3:

stubby straight intake tubes
vertical carb mounting faces
two mounting studs per carb (SU H4)

TR3 through early TR4:

stubby straight intake tubes
angled carb mounting faces
four mounting studs per carb (SU H6)

TR4 through TR4A

long, curved intake tubes
angled carb mounting faces
four mounting studs per carb (SU HS6)