Did the same thing a couple of days ago. I had to put some 1x6 under it to get it high enough to clear the sills. The ends were fine, but the middle cross brace was hitting. Installed it myself by sliding it from the truck bed into the basement. Used a piece of PVC as a roller so I didn't have to fight with it.
It's a 42 x 90. Very nice equipment. I got it from
RadAuto. Excellent service and quick shipping. I picked it up at the trucking depot, as it's just as easy to get it from the dock. Shipping was free.
Very happy with it and probably one of the handiest things I've ever added to a fiver.