Rear End Gear Identification

[Shiro Elex]

I've just picked up an 81 Bronco, and on my way home with her, I snapped the pinion off flush at the differential. I looked the diff over, but found no tag at all on it. On my door jamb, it says '14' under the axle section. The truck has a 9" rear, and originally came with a 300, but now has a 400 big block. I was wondering what rear ratio I have. I know it's LOW (numerically), because 4th gear just bogs. I've read that it might be either 3.00 or 3.50, but want to be sure before I go buying a pinion to throw in it to get it the rest of the way home. Sorry for jumping in with my first post as a probable noob question. Thanks!

Sidenote: Anyone know if it's got 28 or 31 spline axles? I'm thinking of just swapping out the whole third member now.

 

[Shiro Elex]

I found a deal on a whole third member with 4.11s and a locker, so I am going to pick that up. Now, I was looking for gears for the Dana 44 I have up front, but have no idea if I need to get reverse cut gears, or regular ones. It's a split axle, if that helps. Also, I'm running 44" tires with a 4 speed. Are 4.11s going to be enough gear for me?

 

[Shiro Elex]

Think I will probably go with the 4.11s. One thing I noticed is it was kind of hard to find EXACT ratios between the D44s and the 9" ratios. I could find a ton of 4.11s for the 9, and 4.10s for the D44. Might just have to go with 4.56s. Thanks!

 

[djshnizle]

Perfect! I think the 400 will pull me along much better than that 300 would have, so I will probably go with the 4.11s. One thing I noticed is it was kind of hard to find EXACT ratios between the D44s and the 9" ratios. I could find a ton of 4.11s for the 9, and 4.10s for the D44. Might just have to go with 4.56s. Thanks!

If I were you I would go with 4.88s if possible... I have heard all good about them and it will help relieve alot of stress on other drive components. 44 inch tires are pretty big for that front end. you should still be at a decent cruising rpm at freeway speeds as well.