Contact the border station for the best answer.  I believe it differs between provinces.  This might be the station you are referring to:
http://www.cbp.gov/xp/cgov/toolbox/contacts/ports/mi/3802.xml
For Quebec you need a bill of sale and the title.  You hand over those documents at Export Control on the US side and then you have to leave the van somewhere on the US side for three days.  They check out the title and if all is well they give it back and you tow it across, then you have to stop in on the Canadian side to pay any duties.
I have heard other people just towed a parts van straight through and weren't even asked any questions about it, but I'm guessing that's the exception rather than the rule.

-Hans
East Coast Vanagon
www.vanaru.com

----- Original Message ----- 
From: "Christopher Gronski" <gronski@GMAIL.COM>
To: <>
Sent: Wednesday, May 03, 2006 8:07 AM
Subject: URGENT - Can I import a vehicle into Canada with one day's notice?

Subject line says it all. I want to pick up a 1987 ( ie: greater than
15 years old) parts syncro from the US tomorrow. Can this be done?
What documentation do I need. I am towing it not driving it. Crossing
at Port Huron Michigan.

Chris