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440 and 8 1/4" diff

10-08-2006, 06:24 AM
Will the 8 1/4" diff hold up to a 440?

10-08-2006, 09:17 AM
To answer your question, I would be inclined to say "No".

I understand from your previous posts that you have a 1971 Dodge Charger with a factory 318. I assume you have an automatic transmission, as well. You also state you have an 8-1/4 rear end.

In the 318 equipped cars of this vintage, Chrysler used the A-904 (light-duty) Torqueflite automatic and the 8-1/4 rear end. Should you decide to swap in a 440 engine, you also need to connect the 440 to an A-727 (heavy-duty) Torqueflite and an 8-3/4 rear end. Otherwise, you will eventually blow up either the tranny or rear end or both and I am not sure which will go first.

That's my two cents on this subject.

10-08-2006, 11:38 AM
It's a 440 still connected to the 727. The reason I asked was because I heard of the posibility of the diff being a 7 1/4". I found a chart for figuring out what diff you got, but it doesn't show me what the 8 3/4" looks like. From what I can see on the chart I have is that the 8 1/4" and Dana 30 have the same bolt battern and same cover design.
Do you know where I can find out what the 8 3/4" looks like, so I can spot one when I need to get it?

10-08-2006, 12:44 PM
The chart you included in your last post shows the bolt patterns for the rear cover plates for various differentials. The reason this chart does not show the bolt pattern for the rear cover plate of an 8-3/4 differential is because there is none! The 8-3/4 differential assembly includes the front cover plate. The front plate and differential assembly pull out of the front of the housing as a complete unit, a completely different design than the rear access plate differentials. This makes the 8-3/4 unique from the other differentials out there and easy to identify with a quick visual.

To spot an 8-3/4 differential, look for one that does not have a rear cover plate, just a round dome moulded in the case. The differential assembly will have bolts in a circle around the front side of the housing.

10-08-2006, 02:32 PM
There is a Dodge truck at the junk yard right now. If it has a Dana 60, should I just get that? That's what my Power Wagon has on the rear. The front is a Dana 44. Although the chart doesn't say the size of what's inside. Do you know what should be in it?

Another question: Since this 440 and tranny are out of an 80 motor home, I keep hearing that the gear ratio is going to be too low of gearing for the car. What's the best solution? Is changing the grear ratio in the diff good enough, or does the tranny need to be swapped for a car version?

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