Props for trolling motors

[wiperhunter2]

Some years back the gears in the foot of my 6 hp Evinrude got striped and the new parts were too much to make it worth while to repair. I finally found a used motor with a good foot and changed them tonight. All was fine until I when to install the prop, that is when I noticed the old prop was a three blade and the new one is a two blade. My question, for anyone that might know, which prop will be the best for slow trolling and which one will give me more top end speed? If looks like both props will fit.
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