I am doing an SAS on my 84 F-150 using 78 Dana 60 out of an F-250. I am using leaf springs. Would it be easier to build a crossmember and run the 32 inch spacing that the 78 has or move the spring perches out and run the 36 inch spacing of the 84.
it can be done eazy to make the wider just move the perch on the pass side over and build on for the driver side so half of the spring rest on the cast part and the other half sits on the perch. a guy buy the name of jer i think it was did it and thats what im doing on mine // below from Keith
Basically yeah, the pass side can just be moved. For the driver's side I didn't actually attach to the cast centersection at all because I didn't want to weld the cast, plus you'd have to grind the weld flat anyway 'cause the spring needs to sit on it. Jer bought some aftermarket perches from ORU. I cut the new perch down it's length, about 2/3 and 1/3. Basically cut right next to the center pin hole. The new perches were fully "boxed," meaning they not only attach on either side, but could be welded front and back, too, perpendicular to length of the vehicle. The cut perch was then put up against the stock cast centersection, and we could weld three sides: the radius of the tube on the outboard side, and front and back. This is plenty. The spring then sits about 2/3 on your new perch and 1/3 on the old perch. A bit of grinding/radius'ing is required to make the u-bolt fit the webbing of the centersection, but it's no big deal.
It sounds a lot more complicated than it is..............and of course a pic would be worth 1000 words.