Auburn posi
 

I have a buddy of mine who has a 12 bolt truck rear with a 4.88 auburn posi unit. The grear ratio is too steep for my use. Does anyone know if the posi unit will swap into my 68 c10? My truck is a 307 with a SM465 4 speed from the factory which has a 3:73 gear ratio. Thanks,Jon

Re: Auburn posi
 

I belive it will fit but check the Auburn web site to confirm the carrier change over ratio

Re: Auburn posi
 

It should. The carrier break for truck 12 bolts is 3.73 and up. On cars it's 3.90 and up. I have a set of aftermarket thick gears on my truck 3 series carrier that I ran in my Jimmy. That would be the one concern that they are aftermarket gears or something, but most likely not a problem.

Re: Auburn posi
 

x2 ^^

the break off is 3.73-down. Auburns are awesome units. my project has a factory posi and one of the refinements once running will be changing to Auburn for a stronger set-up. My rear was a 3.08 and I changed it to 3.42 for more 4spd (car) grunt while remaining hiway friendly w/o overdrive, and still do well with if I get to that

Re: Auburn posi
 

The only real drawback to the Auburn unit is the cone type units are non-rebuildable.

Here is West Coast Differentials Carrier Break Chart. This is a good source for just about any rear diff. If you ever look at a 3.73 truck gear set, the ring gear is really thin because of the pinion gear diameter and the fact that the 4 series carrier is 3.73 and up.
http://www.differentials.com/technic...carrier-breaks

Re: Auburn posi
 

Gear ratios can confuse people. Mike and I are saying the same thing, but he's saying "up", meaning higher number and I'm saying "down", meaning lower gearing. The higher the numbers the lower the gearing. Just wanted to clear that up. I always ask,"Do you mean higher gears or higher numbers?", to be sure when getting info. I'm starting to use tall & short to be more clear...but not consistently :cool:

Re: Auburn posi
 

Agreed. Most people don't have a clue what tall and short mean so it adds an additional degree of confusion! :lol:

Re: Auburn posi
 

I don't understand what you mean. :lol: