I needed to start replacing 48" diffusers that where installed in 1958. About 1/2 of them are broken and permanently stuck closed, which was starting to cause cold/warm spots in the house.

This model fit the 2 most important dimensions - Width and Depth - perfectly. It's just 1/2 inch shorter height wise than the old ones. I touched up the paint to make the difference less obvious.

I only ordered one to make sure it fit; I'll be ordering a bunch more as I go through each room and replace old models.