if I'm not mistaken, the factory w.b. options were 137" and 161" and I think a longer one. A factory bed will leave a gap on the short w.b. I thot I'd also heard that the distance between the inside of the inner duals is narrower than a regular bed's wheel wells. I've been trying to figure out how to make my f-superduty axles fit my f-350 cc also. I'd thot of lengthing the f-sd frame to the 168"wb and then swapping over the cab and bed, but I would still have the narrower rear end issue. I talked to one shop about widening the rr end so that the spring pad spacing would match the "pickup frame" spring spacing. He quoted me $2500 to widen and to install an ARB. One trailer building place quoted $3500-$5000 to lengthen frame, if I brought in only the rolling chassis, no body. Seems faster/easier/cheaper route to widen the axle, getting the ARB in the process, which isn't available for the Ford D-80, but is for the Dodge D-80. And no frame strength issues either, after cutting and lengthening.