39 5/8" x 17 1/8" x 5 7/8"
(1003 x 433 x 148 mm)


These are the S900 dimensions....

I would suggest the Guardian 61 case ....
in side there are are four adjustable Velcro square Foam blocks that you can put anywhere on the sides to compensate for the few inches of extra space if needed....
http://www.finecases.com/browse/guardian-cases/guardian-cases-3070.html