building 8 3/4 489 section

I'm disputing the only 12 second comment. I was just under 12 and built the 489 case and it wasn't the axle or the spool it was the caps in the back holding the ring gear and spool. And this was a 4 speed car or 5-speed it doesn't matter, it unloads and reloads the rear end between every gear it is very hard on the rear end. You can see my threads wear I never even tried to 7 and a quarter the eighth and a quarter lasted quite some time and I sold it before it went out and I built a 489 case 8 and three quarters full new gears blah blah blah and it was toast in 30 passes or less. with a 4 Speed car I would build a Dana if I want insurance like I did. Another one of my expensive lessons I'd like others to avoid. Do it right the first time and be done. Especially if you have the bug to go faster. For me it was 1200 bucks for the eight and three quarter and 1200 bucks for the Dana.

daveakre said
I think he's just talking about building another center section, not a whole new axle.

For a car that's only going 12's, all those billet parts are probably way overkill. I would still consider running a spool on the street if your tires are tall. (28"+) The best way to pick gears is to use a calculator to help you figure out what your theoretical top speed in 4th (or 3rd on an auto, whatever 1:1 is) will be. Ringpinion.com has some helpful pages for that. Figure out what mph you will eventually want to trap in the 1/4 and gear the car so you'll be right around redline at the stripe.