i have a 2007 uplander..it came with no side rails on it..i bought some from a local junkyard and had a body shop install them...i am now wanting to purchase the crossbars for them..Are the adjustable width wise?...the body shop didnt put my side rails on to what the factory measurements are..they are only off by about 1/4 of an inch...would the factory ones still work?any help would be great..thanks