That's a tricky task again, no answer in my sources. Built before 01.05.56, changing-date of german license plates. Based either on Mercedes L 6600 / L 315 with external pullman-cab or on LP 315. First, I think it is a LP 315 with a very early version of the Wackenhut cab.
But there a minimum two other opportunities. If necessary, I'll go on sampling.