Hmmm, cattle cars ... yes, I do have recollections of them based on personal knowledge. Needless to say, the Marine Corps version was the base model when compared to the luxury models enjoyed by the other services.
The Marine Corps does not believe in such silly things as seats - you can pack more in if they all stand. Certainly that applies with any transportation used for Marine recruits. And naturally they were GREEN!
I don't recall them being used at MCRD San Diego, but I do recall a thrilling ride to and from old Camp Matthews (the rifle range) with full pack and rifle for the range portion of boot camp. 16 man squad tents with the sides rolled up during the day in the winter and no heat. Everything you owned (including your bucket) jammed in to a sea bag and locked to your bunk while you were on the range. Ah fond memories .. best enjoyed through the lense of time.
I know I've seen them used else where, like Subic Bay as a fleet liberty bus to get the Marines and squids back to ship for cinderella liberty. I believe those had seats, and were probably Navy gray. Remember "cross decking" after a fun evening in town?
Speaking of being treated like animals:
Many, many years ago during one of my stays at the beautiful, parched brown hills of Camp Pendleton I was traveling back to the barracks for a shower after a fun day greasing road wheels and such when I passed the Camp Pendleton base band all standing in a cluster. Next to them were several duces with their tail gates down.
As I approached I heard one of the pampered few commenting to his peers:
"Now I know how the infantry feels ... "
As you can imagine, the band normally travels by nice buses. Seems that their limo broke down and they were going home the hard way in the back of a duce. (they had been in our area for a graduation at one of the Marine Corps schools at Camp Horno - Cooks and Bakers I think)
Being a very salty Lance Corporal, having returned from my first overseas posting at Okinawa, I felt it was my duty to educate the poor misguided slick sleeve (private). So I addressed him by rank and took him in tow. As luck would have it our Company Gunnery Sergeant was also passing by and asked what I was doing with the horn blower. I explained his comment and stated that since he had expressed interest in life as a grunt I was taking him to see their NCOIC to see about a transfer or at least a familiarization course. The gunney allowed that I had the right idea but suggested that we might just want to toss him in the POL shed behind the Ontos park until the band left. Then take him for a walk in the hills. Of course poor bandsman was pale and shaking, having never had personal contact with actual Marines from the Fleet Marine Force before. About that time the NCOIC of the band showed up, had a short talk with the gunney, grabbed said bandsman by the stacking swivel and drug him off for further education.
Ah the good old days .. always better from a distance with a beer or two!!