8 1/4 sure grip questions

I've got an 8 1/4 2.94 open diff that I'll be upgrading with a sure grip and either 3.21 or 3.55 gears. My Scamp has a 318 that been bored and stroked to 327 running thru a 904 tranny. Aside from the usual red light race, it won't be taken to the drag strip or driven on the highway much; just a city cruiser taken out on weekends.

1. From the little bit of reading I've done, there are a few different "sure grip" units I could buy (Auburn, Detroit Truetrac, Powertrax, Dana). What is the difference between them and which one should I consider?

2. If you were in my shoes, what gear ratio (3.23 or 3.55) would you put in?


Tks....