If I understand correctly, you are replacing your manual SR frame w/one from a 300D, which is an electric SR, to use w/your manual SR. In this case, yes, you will need the two side lifting tabs you mentioned. These aren't sold separately as they are spot welded to the frame. I suggest you cut the tabs from your manual frame and re-spot them to the 300D frame. You will also need to use the 2 plastic stops on each side that guide the stopping arms. These too can be used from your manual frame.

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