7 1/4 to 8 1/4

[jeffduster]

Im lookin to get an 8 1/4 for my duster i finally found one. it came out of a duster but a 75 i dont think that matters same length, before i get to excited about buying it. What would i need to mod. to get it under there, would i have to shortin the drive shaft? the car it came out of had a 904 in it. its been about a year an a half of not having my duster running and really excited i found a really good deal on a rear end.

 

[jjr426]

you need to make sure you get the u bolt shock brackets and if possible the u bolts as the 8 1/4 is different than the 7 1/4. If the car you are looking at still has the rearend in it you can just take them off that car. If not the 8 1/4 stuff is the same as any 8 3/4 a b e or c body i believe. You will also have to shorten the driveshaft for the 8 1/4 other than that it will swap right in only other difference i can think of is e brake cables 71 down had different than 72 up so if your duster is a 70 or 71 you may need different e brake cables I hope i didnt forget anything but if i did im sure someone will finish up for me Good luck Justin

 

[dgc333]

If the shock plates aren't there it's quite easy to slot the holes on the 7.25 shock plates to accept the larger 3" u-bolts.

If I recall correctly when I did this I had to have the drive shaft shortened 1.5". If the car the axle is coming from is another Duster try and get the drive shaft too, it will save having to cut the one you have.

 

[rumblefish360]

When I did my 7 to 8 swap, I shortend the drive shaft just like dgc says he did. 1.5 inchs. On the plates, I grabed new plates. From Just suspension or MP parts, you can get them new. The Smaller tube size of the 7 is the reason you'll ethier slot the plates or grab new ones. I'd do new U bolts, there cheap enuff.

My plates were thin from rust and the U bolts snapped. All 4 of them Rusted bad.

The rear I picked up had no backing plates. And that was real good for me since I had 11 inch gear from parts cars just for this rear swap project. Once the backing plates were on, basicly I grabed all new gear to put on the plates except the drums themselfs which were in good shape.
(The 11 inch brakes were from a '78 Cordoba and were a direct bolt on, no, zero, zilch in swap problems.)