I recently had a chance to help one of my close friends remove his dead wfco converter from his wfco distribution center.
We replaced the 55 amp wfco with a PROGGRESIVE DYNAMICS 70 amp with charge wizard.
A few years back I replaced mine with the same and only had to trim a corner of the housing.
Well, wfco must have changed the case design a little bit or PD has made there 70 amp unit a little bigger.
We had to cut the whole back of the converter housing out to move the new PD unit back a 1/2" to clear the front cover.
Total install time was about 45 minutes.