1949 Jeepster fuel pump replacement

I am in the process of replacing the fuel pump on my 49 Jeepster with the 4 cyl flathead "go Devil" engine. The original (that I know of) was a dual pump, glass sediment bowl on top with a vacuum pump on the bottom. The person I bought it from changed the W/S wiper vacuum system to come off of the manifold. Consequently I wanted to put on a pump without the dual diaphragm. Could not find one with the sediment bowl on top. Ada has a china knockoff that is not even the same design so I opted for a Carter part number M2195 which fits the "Go Devil" engine. A friend has a 1946 CJ-2A with the same engine that has a similar pump on it. My question is this. The original dual diaphragm pump has a spacer between the pump and the engine block. I read somewhere to always use the spacer. My friends 1946 CJ does not have a spacer. What are the pros and cons of using the spacer or not?. I don't want to experiment and damage anything in the process. Any suggestions? Thanks in advance. Richard

The spacer is not used on the single diaphragm pump.

Thanks for the feedback. Now I can get it running again. Richard I forgot to mention in my original post that the original pump had failed and that was the reason for the replacement.