pre approval is pretty much the only way to go. Im not sure about WI but in AZ the "spot delivery" is a very common practice by alot of dealers, ie you sign the paperwork while the financing is pending, then you may get a call a week or two later saying it wasnt approved and then it becomes a huge mess. I just bought another truck a year ago, I went to my credit union out here and they gave me a pretty decent rate,but when I went to do the financing at the dealer, they wouldnt honor that rate so I ended up going through the dealers FI dept and went with Wells Fargo, ended up being better terms and rate in the end anyhow.