Hello,
I have a'78 Dodge D100 stepside.  It has the original 727 trans, but the 318 has been changed over to a 360 and the rear end is a Chrysler 8 3/4"(741 case). I am having trouble with this rear end, and a friend has one out of an 85 or 86 Dodge truck that he will give me. My question is: can I swap these over with no problems? Just wondered if everything will fit, or will I need to make some modifications?  I have no more info on the new rear end right now, so this may not be enough to go on. Thanks for anyone's help or suggestions....Layman's terms would be good 'cause this is way over my level of expertise!  Thanks!  

can you read a tape measure. if so, get a note pad, measure your rear. [track] distance, center of tires, spring mounts, *** and spring, c. to pinion c. Compare to other rear and note the difference.   c.= center. Hope this helps. still confused? post back.  

Thanks for the help!  It will fit but I didn't realize that the rear end came with the whole back end of the truck minus the bed! That is a little more than I feel comfortable doing plus would have to get it hauled to my house. To fix my original problem, all that I really need is an axle flange for the left side.  Mine is warped, and whoever owned the truck before me has used a grinder on it.  I cannot get it to seal, and can't seem to find a replacement anywhere.  I also noticed that there is no adjuster on that axle.  Anyone know if it is supposed to have one?  Help locating these parts would be greatly appreciated!  I think I'd like to try to fix what I have rather than swap out rear ends. Other ideas welcome too!!!  

Pull your, and doner axle, and compare. measure length, count splines, measure bolt circle, measure shaft and flange diameter. if every things the same, there you go.
Adjuster`s on passenger side. or there`s gotta be an aftermarket co. that will sell a new axle. Try dealership parts dept? or call junkyard with nationwide parts callout. Ask what years interchange. have fun .  

Ha! Ha!  I found a flange, and I think I am back in business! This seems to be the simplest way to go.  Now if I can just get it all back together....been so many days since I took it apart! Unfortunately, I got ahead of myself and took the whole rear end out BEFORE finding out about the other one!  I bet I won't do that again!Thanks for your help and the info about the adjuster.  It does have one on the passenger side but none on the driver's, and someone told me that they thought it should have one, but weren't sure. It took half a day and a dying cell phone but I finally managed to locate the flange.  I'll let you know what happens...Thanks again!