Detail of attachment points to body. Fig 21 shows what appears to be a 'safety catch' to prevent the main latch coming open, although this isn't shown in the Parts Catalogue (image from Leyland Drivers Handbook).
Front fastenings to top of screen frame. Exactly the same as for the soft-top header rail - originally AHH6262 for cars up to chassis number 38387, AHA7709 from then to the end of production for the UK, AHA8491 for North America.
(image from Leacy MG Ltd)
The sides use the standard tonneau bar sockets AHH8391 screwed to the body, shown here mounted behind the hood frame as the sockets are also used for the tonneau or hood cover bars.
Bracket AHH7202 is screwed to or through the body of the hard top, with bracket locating AHH7203 between the bracket and the socket providing the adjustment between top and body, from a screw going through a slot in the bracket into a welded nut on top of the locator. Another screw goes through a hole in the tonneau socket into a threaded hole in the locator to resist pulling upward from air pressure or Bernoulli effect (drawings from Leyland Workshop Manual).
Side bracket locating detail (image from Leacy MG Ltd)
Slots into tonneau/hardtop socket AHH8391, with the hole for a screw to go into the side bracket above.
At the rear bracket AHH7199 also screws through or to the hardtop body ... (drawing from Leyland Workshop Manual)
... its bar slotting under the same retaining plates 14B1730 screwed to the tonneau panel as used by the soft-top (image from Brown and Gammons)