Hi Brian from Buffalo and welcome to the forum.
You came to the right place for answers.
Clayton was a furnace once made by another manufacture, the original designers of the furnace back in 1983, but they got into financial trouble and U.S.Stove I believe bought them out in the 1990's. The color of the original Clayton Furnace was a light beige. If I remember correctly, U.S.Stove changed it to red and then to green.
I have a lot of experience with the Clayton furnaces. U.S.Stove is correct in telling you that there isn't any difference between the 1600m and the 1600g models. What they didn't tell you is that the are a few slight differences in the electric controls. Depending on who is selling the furnace, whether it be a hardware store, Tractor Supply, or a catalog store, there were just a few slight differences between them. Nothing that makes any one style better or worse than the other.
When the 1600m came out, it could be had with either a manual draft spinner or an electrical thermostat controlled actuated spinner. Then they came out with the 1600g with a thermostatically controlled combustion draft blower on front in place of the manual draft spinner or electrical motorized draft spinner. This was a great improvement with the performance of the furnace. So much that they offer this thermostatically controlled combustion draft blower as a kit to upgrade a 1600m.
Now the 1602r is the new style Clayton, which they now call Ashley. It is now back to red color. The 1602r has two smaller blowers in the rear for forced hot air circulation, while the 1600m and 1600g have one large circulation blower.
I was once in contact with the Vice-President of Sales and Marketing and sent him some pictures and links to NEPA about my Clayton stoker conversion. Since then, in my opinion, it appears that they didn't like the idea of someone converting their Clayton to a stoker. The manuals got vivid about not to be used for stokers and they seemed to have dropped the Clayton 1600g from its line and replaced it with the new Ashley 1602 model line.
Anyway, the Clayton or Ashley 1600 series line of furnaces are a great designed stove. The only fault that they may have is the welds around the feed door, where the one piece of steel meets together that the feed door seals the gasket to. I have found that this area is usually just tack welded and not a full bead. I have had a few Claytons crack there and had to be welded at that point.
Here are a few links to the Clayton projects I have posted. successfully burning anthracite coal in a clayton furnace CLAYTON FURNACE WITH DUAL READING STOKERS LAST YEARS CLAYTON STOKER PROJECT CLAYTON FURNACE FIRED ON WOOD
So, sit back and enjoy reading. With your new Clayton installed, you will be in for a warm winter in your home.