Let's play.....Name that differential!!!
 

Looks like a Dana 60 by the bolt pattern(using the LMC book)...am I right? If so- a 3.54 is as tall a gear they make?(in LMC anyway)

1989 R3500 dually.

Re: Let's play.....Name that differential!!!
 

Dana 70.

Re: Let's play.....Name that differential!!!
 

If you look at the webbing that is cast as part of the center section it will tell you what it is. On any Dana they cast the size numbers in the webbing could be top, bottom, or ether side.

Re: Let's play.....Name that differential!!!
 

The 70 is easy to spot by the extra bit of meat below the bottom right area of the diff cover. The 60 doesn't have this.

Re: Let's play.....Name that differential!!!
 

Dana 70, check the numbers and it will tell you if it is an HD or a regular.

Re: Let's play.....Name that differential!!!
 

I planned to clean it tomorrow(oily- just on the chunck). Thanks for the info. Trying to figure out 1) what gear is in it(rediculously low) and 2)then what gear I want to run...hwy friendly(75-80mph) towing 5000#'s.

Re: Let's play.....Name that differential!!!
 

my money is its got 4.11 in it

Re: Let's play.....Name that differential!!!
 

The speedo it reads ~83 at 70mph. so it isn't the stock gear/rear end...or They messed up the speedo gear...not sure why it is that far off. 83 mph indicated is 3300-ish rpm.

Re: Let's play.....Name that differential!!!
 

Or the rear tire sizes(diameter) may have been changed.

Verify if tire size is stock first to save headache.

Re: Let's play.....Name that differential!!!
 

if its a dually 1Ton its a Dana 70HD