I was going to chime in here and I see you figured it out.My 92 is 8600 GVWR. Looking for rear brakes I did see there were larger GVWR options available for that year so that is likely where the FF came in then.
Yes vans did get the 14bff throughout the 25 years run but it wasn't as common as the trucks.
I had a few vans myself and converted on to 4x4
