Rack & Pinion retrofit???

I have a 78 280Z which is stock...or so I thought. I am restoring the engine compartment and putting in a new engine. While inspecting the rack and pinion assembly, I found that I had a torn bellows/boot so I pulled the assembly to inspect it and replace the bellows on both sides. When I ordered new bellows, the bellows that I recieved had a 1.75 id on the end with the large opening. I also checked the size of some other bellows for a 280Z from my local auto parts stores and they all have the 1.75 ID opening.

My rack and pinion bellows ID is only 1.375"!!!!????? Other wise the assembly seems to be identical and fits the frame and wheel assembly according to the original design. I am suspecting that the original rack and pinion was replaced with my current one.

Does anyone know what model or year the current assembly may be from? I would also like to buy some new boots to fit this current assembly so let me know if you have a source. I have attached a pic of my current assembly. Thanks