A basic flange puller will pull the balancer. You can change the seal in the truck but check the seal mating surface on the balancer. If the mating surface has a groove worn in it the new seal will still leak. They make sleeve kits for this problem but I have never used one. My balancer had this problem but it was beat anyhow so I replaced it. I highly recommend using a balancer installer tool. This Cal-Van is the same as the Snap-On/Blue-Point one for half the price:
http://www.thetoolwarehouse.net/shop/CAL-388.html (they have a minimum order $ but they have good prices and customer service). You can probably get away with a cheap puller, I like the OTC 525 though, good for the price and their pullers are all interchangeable.