Not a BA212, what is it? VAX Question

Well, this is truly interesting. I cleaned up and checked out the VAX 4000/200 I got in what I thought was the BA212 cabinet. But it isn't. The tag on the side calls it a BA400 series (and the power supply certainly bears that out) but it is like the BA212 in that the card cage is _behind_ the drive bays. The drives are your standard BA440 type removable (who ever invented that guide/track system does NOT get any bonus points) and the front cover doesn't have a door, only a cover to prevent the drives from being removed when it is in place. Does anyone know what chassis type this is? The system was built in 1991 (see, its on topic now :-) but I've not got a later version of the MicroVAX Technical Handbook which might describe it (the version I have describes the BA440 with the VAX 4000/300) --Chuck