Revington TR have three alternator/dynamo brackets available.

058912 Original TR2-4A dynamo mount. This bracket has its legs 102mm apart measured externally and 94mm internally (the material is 4mm thick). This bracket suits all dynamo fitments and most Lucas type alternators that were a common fitment through the 70 s and 80 s
RTR1068 This bracket fits in the same way as 058912 with its forward leg in the standard potion where it will sit up against the engine front plate, the rear leg however has been moved forward to the middle of the bracket to suit some alternator types.
This bracket has its legs 35mm apart measured externally and 27mm internally (the material is 4mm thick).
RTR1068X This bracket fits in the same way as 058912 with its forward leg in the standard potion where it will sit up against the engine front plate, the rear leg however has been moved forward to the middle of the bracket to suit some alternator types.
This bracket has its legs 44mm apart measured externally and 36mm internally (the material is 4mm thick).

For dynamo mounting detail see plate M in the TR4A original parts book or web site.