TrueTrac Rear Differential Order

I ordered a few parts from Summit Racing yesterday..

I decided to go ahead and order the TrueTrac differential and ring gear installation kit. By purchasing by October 31st, I receive $40 in Summit Bucks which is basically a discount on my next purchase. Once I receive the Summit Bucks, I'll order the ring gear and pay the difference.

The TrueTrac differential is great. Unlike others, it is a helical gear design which does not use clutches. There are no parts inside which would wear out. It engages so smoothly it is suggested for use even on front wheel drive vehicles. Finally, when engaged, it is a direct connection of the two rear wheels rather than a partial locking of the secondary wheel.

However, it is hard to justify sending so much on the rear axle based on the budget for my build. I have the $86 from the carburetor, $40 in Summit Bucks, and $50 in cash back bonuses on my Discover card. This helps a little and I hope to sell more unneeded parts to help make the purchase reasonable.

I'm now trying to determine which rear gear ratio I should use. Since I am going to be using the 3 speed for a while, I want something which is not too bad on the highway. I'm not sure if I will ever get a 5 speed but if I do it would be best to not need to replace the rear axle. While a 3.25 or 3.40 would work they would not be ideal. I guess with either one I would probably want something larger.

I'm leaning toward the 3.25 gears right now. They should put me a little under 3,000 RPM at 70 whereas the 3.40 gears would put me around 3,100. Of course, there would be a slight gain in performance by going with the 3.40 gears. Decisons. Decisions.