The chestnuts and bays are fairly straight forward. Plastic type for the most part is a simple identifying feature and the colours are dissimilar enough to be distinctive.
The first model is the 1995 regular run. Compared to the regular run original Swaps next to him, he is very red and usually without markings. The original Swaps can be found with a variety of leg markings, rare facial markings, and is usually brown-toned in colour. He also comes in old or new plastic while the 1995 release is only found in new.
The fourth model (bottom right) is technically chestnut as, if one looks closely, he is lacking black points, but from a distance he make a fine bay. This model is the 1991 special run and is only found in old plastic and should have a pair of fore-socks. The bay model to the left is also a special run, this time from 1996. He is of new plastic and should be without any markings.
The buckskin models are both special runs, and are both only found in new plastic. The first model is the 1997 special run and is a rather shocking keylime pie yellow. He should have hind-socks, white fore-feet and may come in the full range of 1997 plastic types - normal and chalky have been seen, we are still looking for a translucent example.
His companion, the 1992/94 special run, is significantly darker, though still yellow. This run should be a nice dried mustard colour with no leg or facial markings.
These two special runs fall into the creamy/greyish/dun category.
(left) Model and picture owned by Elizabeth Emswiler and used here by permission. (right) Model and picture owned by Sharon Walbridge and used here by permission.
The model on the left is the new plastic 1996 Inroads Interactive special run. Like the models above, he may be referred to as dun, but unlike the other models, he has soft grey-ish chestnut points. He should have one off-hind sock and a soft bald face.
The 1990 special run is, of course, old plastic. It usually has a semi-gloss finish and was called rose grey. Though this model looks more like a slightly off-colour alabaster, others can be more heavily shaded. All models should have some quantity of soft, peachy shading and a grey mane and tail.
The remaining greys are much darker than the models above.
(left) Model and picture owned by Sharon Walbridge and used here by permission. (right) Model and picture owned by Heather Forrest and used here by permission.
Though both models are dark grey, the new plastic 1995 special run is more of a roan with his dark head and lighter body. He should have black points and a brown tone to his shading. His hooves and lower legs should be a reddish brown. The 1990 special run is only found in old plastic and usually has a semi-gloss sheen. He should be a uniform steel grey with black points and no white markings.
Many thanks to Elizabeth Emswiler and Sharon Walbridge for providing pictures of the missing Swaps!