You can't put a locker-spool in your front end. Well... you could but you wouldn't be able to really turn or anything.
They're not called rear-ends they're called differentials. And finally, breaking your axle was probably more due to wear and abuse then anything. No straight axle truck is going to get amazing traction on road or even off road in some situations but it's much tougher and really the only option you have.
You have two rugged differentials, put a posi-track unit in the rear and rebuild your front as well. You won't be able to spool your front and you won't want to spool your rear. Ever have a welded rear end? A spool is the same thing basically. You want a posi unit out back and if you really have the bucks, a air or electronic locker up front so you can control when you need it to lock because it can't be locked all the time.