Relay damaged Power Distribution Box E350 Motorhome
 

I have a 94 Shasta motorhome with a Ford E350, 7.3L diesel engine. The back relay in the "Power Distribution" box (man fuse box under the hood) failed and burned down into the box, effectively ruining it. It appears to be an integral part of the wiring harness for engine and transmission. Help! Dealer says wiring harness, fuse box, no longer available anywhere in the US. It is not available in any of the dozen wrecking yards I checked. Any suggestions?
Perk