All of the bay models here are made of old plastic; only one is a special run. The top row of bay mares are all regular run #5038s. The 1991 Sears SR is a very red bay with (typically) four very distinct socks. #5038s can be very similar, in some cases nearly identical, to the SR, but they are generally more brown-toned and their socks tend to be more on the vague side.
This collection of chestnut Morgan Mares are all made with new plastic. The top two are variations of the regular run #5185 from the mid-90s (#1 & #2). They are much redder than any of the other chestnuts, including the two old plastic models in the pictures below. The catalogue model is shown with one near-hind stocking, but stocking-less models are fairly common and multi-sock models may be possible, though I've never seen any.
#3 is the very pale apricot chestnut 1996 JCPenney SR; I have a slightly darker version, but with her heavy panagre shading, there is no confusing her with any of the others. #4 from the 1995 JCPenney SR set is a flaxen chestnut with four-ish stockings and a rather yellow-toned coat. #5, the other flaxen chestnut (also could be a silver dilute) is much, much darker than #4. This Sears/JCP 92/94 SR's flaxen mane and tail can often be oversprayed by the body colour, but she's distinct enough from the other Morgan Mares that she would be difficult to confuse with other runs.
Models and pictures owned by Elizabeth Emswiler and used here by permission
These two lovely mares can be troublesome to identify. They're both made with old plastic and their colours are close enough that variations within their runs can easily resemble the other. In general, the regular run #5040 on the left is a bit darker and has more of an orange tone to her chestnut coat. The 1990 Sears SR on the right tends to be a bit lighter with more of a brown tone and her mane and tail tend to be several shades darker than her body.
No, these mares aren't both black. The model on the left is a regular run #5039; they're always old plastic and are quite jet black. On the right is the new-plastic 1997 JCPenney SR is a very dark seal bay, though you could pedigree her as a sun-faded black. The RR tends to have some number of socks while the RR tends to stick with light coloured hooves, though sometimes the colour can creep up the legs a touch to resemble very low, faint socks.
Many thanks to Elizabeth Emswiler for generously contributing pictures from her collection to help complete our line-up.