Hi
The M989A1 is the modern version of this trailer - there a number of photos of this on the web and you can find the TM at
http://www.logsa.army.mil/etms/online.htm. It is manufactured by SEISTL and you can find some dimensioned drawings on their site at
http://www.seistl.com/products/trans/hemat.html,
http://www.seistl.com/images/pdf/hemat.pdfThe M989 was used in Desert Storm in 1991 (you can see one in the background on DML's MLRS box) and looks completely different to the A1. There are very few pictures of this on the web - there are a few small ones in the HEMTT section of the Oshkosh website, but not much else. There is also a clear photo of a HEMTT and M989 in the Verlinden book on the MLRS.
The best references for the M989 comes from the TM, available from LOGSA (although some of the drawings are a bit suspect - see below). There is also a line drawing in TB43-0209 - COLOR, MARKING, AND CAMOUFLAGE PAINTING OF MILITARY VEHICLES, CONSTRUCTION EQUIPMENT AND MATERIALS HANDLING EQUIPMENT, also available from LOGSA.
Unfortunately, the line drawings and the TM show conflicting shapes for the back of the trailer, and none of the photos show this area. Some the 'detailed' diagrams in the TM seem a bit generic - IIRC I saw the same tyre-changing diagram in both the M989 TM and the M925 truck TM.
A while ago I set out to make a CAD model and detailed plans for the M989. I finished about 70% of the CAD and actually built part of the frame before I decided to put it away until I found more references - if anyone can help me in this regard, I'd greatly appreciate it.
I posted some images of the CAD model here:
http://groups.msn.com/armorama/edcarmansalbum.msnwCheers
Ed