After the BAR merger, an inventory of BAR rolling stock found the hulks of F3A’s 40 & 45 sitting in the Derby deadline, and rather than scrap them they were handed off to the Portland shops to be reused.

At Portland they were gutted, placed back to back on a set of class I trucks, fitted with class I electrical gear, then repainted in the centennial paint scheme BAR F3 #42 had, and put out on the line as a 10000HP motor (like the actual class I’s, but about 9000 pounds more tractive effort thanks to the larger & heavier F3 carbodies.)

This is a fairly tall unit; it stands 15'7" (over locked down pantographs) above the rails, so it stays on lines that are at least plate F; this includes the BAR from Bangor to Brownsville Junction, so it does actually see some service on the BAR.

In a more sensible world, this unit would have been classified as a class I3 (and then the actual class I3’s would have been class I4 instead), but the Portland Shops did all the paperwork and cast the builder’s plate as a class FF3 due to it being built using two F3 carbodies.