I have just bought a 1983/84 110 county station wagon. It had the series style doors and the original aluminium door tops. However land rovers design for these door tops have frustrated me. The two large bolts that hold the aluminium door tops to the door bottom are made of steel and most have rusted to such an extent that they've just snapped. So I've got perfect condition door tops but no way of attaching them back to the door.
They appear to just be a tight fitting that is pressed in. But any ideas how to repair them?
With the rear doors I'm not so worried about being able to take the door tops off but I'd like to still take the front ones off without paying for new door tops.

A common problem on Series vehicles, which share the same door design. You could weld a new bolt section on to the remaining stud, or drill out what's left and bodge in a nut and bolt.

Had this problem with my series doors ,i cut a square out of the inside of the door top to get at each bolt and welded in threaded rod to replace the old rusted studs

Beware they need to be welded at the right angle and if the frame inside is as rusty as mine were it will be hard to weld in the rod and you will need to weld up the four holes you cut to access the insides of the doors !

They are not pressed in they have a thread on the end of the stud (part no VYR200010).

Welding in would be an easy solution unfortunately these are aluminium door tops not the steel ones that are on series vehicles. They are the original from the vehicle.

If it's a steel rod pressed into the ali frame, then you might have to try welding additional length to the existing steel, or drill the lot out and fabricate using threaded rod, washers and nuts.