8 3/4 sure grip swap

[squeakfinder]

I'm about to pull the 3.91 sure grip differential and put in a 3.23 open diff. There both 741 cases. I'd like to swap the suregrip if it's not going to be to involved. Do I need to replace the bearings on the carrier or anthing? Can I simply count the number of turns on the adjuster and bolt the 3.23 ring gear to it?

[Chatt69chgr]

Sure Grip

Sure Grip is the Chrysler name for a limited slip differential.  It was optional on the 8-3/4" axles, 1958-1974.  Two styles were used.

1958-1969 used the Dana Power-Lok (# 2881487).  This unit utilized clutches for the differential locking action.  The Power-Lok can be rebuilt using kit # 2070845 ( Mopar Performance [MP] # P4529484 ). In this assembly, axle driveshaft end thrust is taken by the thrust block assembly (replacement # 2881313).  This Sure Grip appeared in the '741' and '742' assemblies.  The axle bearings are: 25590 (Timken cone), and 25520 (Timken cup), (Chrysler numbers 1790523 and 696403).  The Dana Power-Lok can be recognized by its bolt-together assembly, bolts around the side opposite the ring gear, and multiple openings exposing the cross shafts.

1969-1974 used the Borg Warner Spin Resistant (# 2881343).  This unit utilized a spring-preloaded cone friction arrangement for the locking action.  Axle end thrust is taken by the cross shaft.  This Sure Grip appeared in '489' assemblies and 70 and later '741'/'742' assemblies.  The differential axle bearings are:  LM 104912 (Timken cone), and LM 104949 (Timken cup), (Chrysler numbers 2852729 and 2852728).  The Borg Warner Spin Resistant unit can be recognized by its lack of bolts on the side opposite the ring gear (like the Dana), and two openings exposing the preload springs.  Borg Warner sold this design to Auburn Gear who currently offers the replacement Sure Grip assemblies.

Non-Sure Grip differentials can be identified by the large openings in the differential exposing the differential (aka. spider) gears.  There are no springs or clutches.

Interchange Notes:
The two Sure Grip types can be interchanged between the carriers if the matching differential axle bearings are retained.  The outside diameter of the cups are the same between the '741'/'742' and the '489'; the inner cone differs.  The Sure Grip differential can be used as a direct replacement for the non-Sure Grip within the carrier/bearing limits previously noted.

[terrible one]

Well it is definitely an easy swap- the suregrip unit will swap just fine, but no matter what you will have to set the rear end up again which isn't too hard either but requires a few expensive tools, like a plunger dial.