Uhhh, Geof, I don't know whether you knew this or not, but Volvo sleepers are of the integral variety, in that they are built in unit with their corresponding cabs, and therefore are NOT a separate entity, or box. You're not likely to find one unless someone has one that has unceremoniously been hacked off the cab. Definitely not a nuts-and-bolts job.
Just thought you'd wanna know.
Gary