Well, if you don't have the dough to buy a 12 or 14 bolt...........
You can greatly increase the strength of the 10-bolt with aftermarket parts but it will cost some money. First, get rid of the stock differential (carrier) and replace it with a good aftermarket posi or locker (Detroit Locker, etc..) which will increase the strength in that area. I chose a Detroit Tru-Trac and have been really happy with it's performance on and off the road.
Since you are installing a new posi anyway, get the 30-spline version (if the truck is older than about an '87 or '88 you probably have the 28 spline version) and the corresponding 30-spline axleshafts from a place like Moser.
Now finally, just add some good aftermarket gears in the ratio of your choice.
I've done some serious wheeling with a 10-bolt set up the above mentioned way, with both 33" tires and now 35" tires, for about 2 years with no problems..........though I am planning an upgrade in anticipation for even larger tires and harder use.
However, it will cost you........$300-500 for the posi or locker, $200 for gears and bearings, $300 for axleshafts, plus $150-250 for labor. I've always been a fan of the 10-bolt for various reasons, but if you want one to stand up to moderate use you have to pay for it.