I have a 1988 IROC-Z 350 tpi 700r4 with 2.77 gears. It now runs 14.6 in 91 deg. ambient.

The first question I have is what gear would work best for the track?

3.23
3.42
3.73

The second question is should I purchase a rear end or just the ring and pinion?

 

Well you will not be using any of the above 10-bolt gears in your 9-bolt rear. They are NOT interchangeable parts.

Buy a new rear if you want different gears or just be happy with what you have and save the money or increase your engine Horsepower.

 

I had an 85 TA with the 9 bolt borg warner setup. I went to performance gear and they were able to get me a 3.73 set. It just took a month or so. Finding a shop to do it was another story.