I would expect that the original fuser could be put back into place. Good sign that you can swap it out to begin with.
Been awhile, to be honest, but during a time of tight budgets and other circumstances (i.e., a VP of Finance/Accounting who hated computers, IT, and things in general), we often cannibalized printers to create one working printer from two or three others.
However, with the all too common "replace versus repair" thinking these days doing such things may no longer be viable....
Not an issue at all if the printers were out of warranty and we had nothing to lose and any printer we could salvage was valuable.