B-Bod 8-3/4″ Rear For’84 Chrysler Fifth Ave

Tech Question


Rob Snow, Kitchener, ON, Canada, 1984 Chrysler Fifth Ave 318

Hi Mr.E-berg my skill testing question for you is this. Ihave an ’84 Chrysler Fifth ave that I purchased a few years ago orignallyfor a winter car so that I would not have to drive my already rusty 72coronet with 340, 904 T/F, 8-3/4 3.91 gears. As it turns out my Coronet istoo far gone so I want to make the Fifth a sleeper.I know that the engineand trans swap is a no brainer but the rear end is another story.Can it bepossible to swap a B-body 8 3/4 rear in my Fifth Ave? And if so,do you knowif the stock drive shaft will fit (lengthwise) or do you know if a driveshaft from another Mopar will help make this become a very simple swap, ordo I have to get friendly with the nearest custom driveshaft shop? Youranswer be greatly appreciated. Thanks


Rob, it’s very close, size-wize: The typical pre-71 B-body housing is about3/4″ wider overall, and about 1/2″ narrower at the spring seats – closeenough that it’d probably go right in. The propshaft needs to be about 3/4″shorter if your current axle is a 8-1/4″, or about 2-1/4″ shorter if 7-1/4″now.

Several other things to keep in mind:

The pinion angle may need correcting (tapered shims).

I suggest losing the rubber isolators.

The 318 propshaft might fail early-on, suggest shortenting the Coronet one(if it’s not from an original 318 car also!), Even better, have it re-tubed.Old rusty propshafts are an accident waiting to happen.

Overall, I’d rather have a 8-1/4″ in this car…probably strong enough,cheap, light, easy to work on.


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