Differentials: open or limited slip?

[mmwb]

Still trying to figure the beast out. '76 M880. Did these come with limited slip or open differentials?

 

[Recovry4x4]

Open front and rear!

 

[acetomatoco]

But you have full time 4wd with a lock feature in low and high, but they are tough on gasoline

 

[Bob H]

Yes sir open diffs
Dana44 front & dana 60 rear with 4.10 gearing
Posi units (Trak-Loc) are availible for those axles.

.........tough on gas???????????
My M880 gets nearly 48mp4g !
The M886 gets 36 to 40 mp4g!

(mp4g=miles per four gallons)

 

[mmwb]

Appreciate the replies. My understanding is that if a wheel slips on one axle, that putting it in LOC will allow the other axle to engage anyway. Is that correct?

We'll see on the mileage. I am toying with installing an RV cam for more torque, keeping the carter carb--but with a better manifold, and installing headers to help the thing breath. I would expect that that would help with mileage as long as I keep a soft touch on the accelerator. Bob, I don't think 10 or 12 mpg is too bad for an old heavy truck like these.

Pushing snow with my F150, I averaged 6 mpg. I don't expect that this truck will do worse.