I have 3/8, 1/2, 3/4 and 1" drive impacts. I have all IR Titanium series. If I only owned one impact it would be a Ingersol Rand 2135TiMax. That is all you need for pickups. New they can be bought for $300. I buy then new open box on eBay for $250. I would not consider a used one because if someone had it who didn't oil it or had a lot of water in their system, it can be junk even though it looks good on the outside.
An impact is like any other tool. You have to learn to use it. That means feathering the throttle as well as keeping your fingers out of the way of a wrench holding a nut on the back side. A 3/4 is bulky and heavy. We use them on 3/4" self locking nuts on our trucks, but there isn't anything like that on a pickup. All of the cheap impacts I have seen, I haven't seen an advantage over a breaker bar or a ratchet.
