I have an 89 w150 with 33's. its mainly for use driving in my SMALL town. i hunt and fish alot. i do the occasional mudding. I would like to upgrade the ring and pinion in the axles. What size should I go with? I thought 4.10. Also thought about a rear axle swap with disc brakes.

 

forgot to mention 318 with 727 pretty much stock except exhaust and air intake upgrade

 

Those gears should be good.
They should closely match the tire size without being to steep and bringing the rpm's too high for cruising,but still having enough power to move you.