gypomike

you got it bud,,got to change out the differentials,,,might just want to do one,,will give you 3 wheel drive,,if you do one do the front,

 

I just bought a 389 that only had inter axle. Bought a reman rear pumpkin with locker and they installed it. I think it cost me about 3500 cdn bucks

 

Your truck probably has traction control through the ABS, so double check what axle the ABS sensors are on. You probably only have sensors on 1 drive axle. If you only install 1 rear with a locker, you'd get the best traction by locking the rear that does not have the ABS sensors. Then you have 1 locked axle and the traction control will be able help the axle that is not locked.

If you find that you have sensors on both drive axles (possible, but not common), then locking the front diff is the better option.

 

I have a 97 379 and was looking into this very thing. What I found is that a locking center section will not fit in a non locking housing. There is a cut-out in the locking housing for the solenoid for the locking diff.