A thread about someone looking for one.
Sounds like it's too late to suggest you should avoid it?
I had a 1977 E350 based motorhome with a tag axle. It was in the family about 30 years and we put almost 200,000 miles on it. Running a vehicle with a 11,500 GVWR rating at 14,000 pounds takes a toll. LOTS of maintenance. Brakes, wheel bearings, trans, engine, everything on the chassis is highly stressed.
What tag axle does it have? Ours was a Mor-Ryde setup that completely replaced the rear suspension. There's a few other systems out there.