hello macdougall. i have seen many pictures of ad trucks with 70's rears on them. i beleive that those rears are wider than the stock one and the wheels will stick out of the fenders a little.you might also have to move the axle to a position a little further back to avoid the tires hitting the fenders. you will also have to change over to an open driveline as the original has a touque tube. the exception to these 70's rear axles is the one used on some of the blazers. they are narrower and might fit better. in most cases the spring perches need to be relocated to fit on the stock springs. thats about all i got for now . good luck.
