Will a 8.75 rear replace a 8.25 rear w/o problems?

[74ChargerRallye]

I believe that I have narrowed the hum in my rear to a bad rear or out of balance drive shaft.  My question is... Will a 1971 big block charger 8.75 rear, posi 3.55 and drive shaft work to replace my 1974 small block charger with a 8.25 open 3.55 rear?  I have a manual 4 speed, and the 1971 is a 727 automatic.  I am willing to replace the whole rear assembly and springs if necessary.  Any tricks & traps would be greatly appreciated.

[Ghoste]

You will need to swap the rear end assembly but the spring perches should be the same between the two (rear track didn't change over the 3rd gen lifespan did it?).  The driveshaft may give you a little more issue but it isn't a big deal to get a new one made.

[Beer]

I am about to do this, I should be picking up the 8.75 in Jan...(scored a 3.91 Sure Grip in it )...

Planning on Disc brake conversion on it as well on it.

Driveshaft I am swapping to one approx 4" shorter, I am changing from a 904 to a 727.

[Nacho-RT74]

spring perches are diff. Taller and with small hole to spring guide stud on 71. If you want to keep spring isolators and same height I would advice remove perches from one and weld on the new one.

another options:

remove isolators: In that case would it be nice get the lower spring plate where shock fits from donor AND PROBABLY, remove busings what 73/74 spring stud guides carries to fit the rubber pad isolators, then use a new stud guide ( IF really needed ). You can remove just upper isolator and clamp and keep the lower parts though! get the lower spring plate is just if you want to remove everything of isolation stuff.

To remove isolators asembly and get the spring stud guide without the bushing, you could get also springs from donor. If thats the case, get them with the front spring bracket and WITH bolt. 74 and mostly 73 have bigger front bushing, but change came on inner diameter hole of bushing being smaller and with smaller bolt. That requires also then a front bracket with hole to the new smaller diameter. Exterior diameter of bushing is the same. making smaller diameter on center of bushing, they made thicker isolation bushing.

Enlarge center hole of pedestals/perches: With that will be able to fit on isolator clamp assembly AND will get at the same time lower rear ride height, won't need to use spacer block. I think you'll get around 1/2" rear ride height lowered. Maybe little bit more.

[Ghoste]

Is that part of that deal with the oval shaped front spring eye?

[Nacho-RT74]

edited a little bit the earlier post.

I never have seen on a Charger the oval front spring eye, just thicker bushing made with smaller center hole instead bigger exterior diameter.

Not saying they didn't come with oval, just that i never have see locally or on the web the oval spring eye on a Charger. I REALLY think oval spec was for Station Wagons