8 1/4 sure grip rear end , advise needed !

I am going to put a 76 Volari 8 1/4 rear end in my dart. I want to make it a suregrip before I put it in there. I have checked around and here is what I found on the one I want to buy. I have the 3.21 gears in mine non suregrip. I would sure like to find out for sure before I go and spend that kind of dough!
This is the description of the suregrip assembly below. Has anyone ever put one in there 8 1/4 rear end or had one installed. I'm going to take it to a rear end shop and have them do it unless it's real easy and I don't need special tools? Besides the assembly will I need other parts ? Thanks

Get a grip.
Mopar Performance has designed these replacement Sure-Grip differential assemblies to be used with most Chrysler rear axles. They include an instruction sheet for high-performance applications, and are designed for gear ratios of 2.76:1 and higher.
Differential, Sure-Grip, Limited Slip, 27-Spline, Mopar, 8.25 in.,