Welcome to the Forums and the world of Vintage Airstream ownership!
I am attaching a pdf file that contains the information regarding the way that the original Bargman plug was wired. This does not match today's industry standard, but may assist you if the functions of the pins do not line up with your tow vehicle. My suggestion would be to take along a new plug that matches the fixture on your tow vehicle so that you can rewire the coach to match your tow vehicle if necessary (I have had to do this with both of my Vintage Airstreams).
Unless your coach's original coupler has been replaced, it will require a 2 5/16" ball. You will want to know whether your hitch requires a large or small shank ball -- most seem to be large shank, but there are typically two sizes of shanks when looking for new hitch balls on the racks.
I, too, would suggest looking for a hitch with built-in sway control as your coach is going to approach the maximum comfortable size for your Suburban with its 5700 VORTEC V8. My personal preference is the Reese Straight-Line
, the Equalizer
hitch also has a strong following among Airstreamers. Your Ambassador will be heavy enough that you will likely want to consider weight distributing bars with a rating of 800 pounds -- 600 pound bars may work but may be a bit on the light side for your 1500
You didn't mention the distance of your upcoming tow, but the longer it is in miles, the more attention that will need to be focused upon the trailer. If the tow is more than 50 miles, I would consider the following:
- Repack the wheel bearings and inspect the brakes prior to embarking on a long tow. If the records verify that this has been done in the past 12-months, you should be in good shape.
- Be prepared with replacement bulbs and bulb changing equipment to be ready for any burned out bulbs.
- If the tires are more than three to five years of age, replacing them before a long road trip would be cheap insurance -- a blown tire can cause several hundred if not $2,000 or more in damage to the trailer's skin and nearby components.
- If the coach hasn't been on the road regularly in recent times, a set of strap-on or magnetic tail lights would be an insurance policy against the possibility that you may not be able to get the tail lights operational.
Good luck with your Ambassador!