Well, mine's a 1986, as far as I know, it does have the grey plumbing....and nothing's bursted in it. But then again, there was antifreeze in the system when I first hooked everything up with the water and all. As far as the windows, I think that's something that changed in the 1987 models.....from square to radius. At least the 1987's I've seen on the net for sale had radius windows as opposed to square ones like mine. This was due to the fact that they stopped making the square ones. (Window manufacturers). As I inquired about it to Jimmy Davis, and he said I'd have to make my own to replace a broken one....which I did at a cost of only $15.00. Mine does have a 3 gallon water heater, but does have a 20 gallon tank. (Perhaps a difference in the model?!?) Dunno. Mine's also not prewired for the stereo, that's something I'll have to do myself, but shouldn't be a problem. With the shorter reefer, I have plenty of room for stuff.
One other change I've noticed in the newer TM's is the cove used where the wall meets the ceiling is much wider than the stuff in mine. it's almost 1.5"-2"wide, whereas mine's only 1" wide. (I ordered some from TM, and it was NOTICABLY wider.....I had to send it back).
Happytrails.....