Does the coupler that looks just like the normal one but has a projected nose from the spline area fit as a replacement for the stock one?

Yes and no,it will fit but it may be much harder to get your motor back in place if you have limited room,I have to leave my bottom pulleys off my crank to get my motor in because the extra long snout makes them hit the back seat base,Smitty

Yes it is a replacement, But there is a different input shaft that has a extra o-ring on it so you can grease the coupler splines better, like those nasty alpha,s, but you don't have to change the input shaft if you don't want to.