WHich is the right onstar interface harness is right for my car?

[iMSeRiOuS]

I own a 2005 Monte Carlo LT.

Mach 1 was trying to sell me one for 200$

I think the one I need is a SCOSCHE GMOS2B11, but I don't want to waste my money on something that isn't going to work.

Although they've discontinued that part from their site.

[autotoys]

Non BOSE onstar adapter
http://www.autotoys.com/x/product.php?productid=10690

For BOSE vehicles
See http://www.autotoys.com/x/product.php?productid=10691

[iMSeRiOuS]

I was searching this site for the item(s) you posted and I couldn't find them lol.

Is there a definite way to figure out if my system is bose or not?

There is a factory amp installed in the trunk.

[autotoys]

Usually the speakers will say bose on them.

If you visit our DASH KIT department > WIRE HARNESS, THEN GM, there is a section for ONSTAR adapters

[iMSeRiOuS]

I can't see anything on the speakers...

Although in the item descriptions only one refers to the volume control via the steering wheel, and that is the premium sound/bose one.

[autotoys]

Your original window sticker will have the type of radio in your vehicle. It will list BOSE if it is BOSE,.