I believe the windows were built by Better Built Windows. I think these only came with one roller but there is room for two. Your item number 87-183 looks to be the right roller assembly.
Linda
Bob from SWISCO responded:
June 4, 2019
Hi Linda. I agree the 87-183 looks promising. Can you look over the dimensions and tell us if they differ in any way? If its a match, then this could be what you're looking for.