Replaced the front turn signal bulb yesterday - just sharing the experience to make it less stressful for you:

You can't get to it from the bottom or at least I was not able to with the Uplander sitting in my driveway, you have to remove the headlight. The instructions are in the owner's manual but here's a hint: The headlight doesn't just "pop out" like it says in the manual. Once you've removed the locator pin and the 1 bolt on top that holds it on you'll really have to work with it to get it out of its spot. Its a combination of pulling on the headlamp and compressing the gasketing and bumper all around it so it actually moves out of the way. Its really in there tightly!!! I decided to just move it out just far enough so I could reach my hand down to the turn signal/running light socket and twist it out. Fortunately the wire is long enough so when you unscrew it you can pull it all the way up to replace the bulb. Replacement is a 3157NAK or equivalent. I had a 4157NAK in the garage and its the same bulb so I used it. One you've replaced it, it takes a little finesse to get the headlamp back in - be gentle, you don't want to break anything. You'll have to push the gasket back in as you go.

Hope this helps someone.