Does a '56 ford Customline have a 8 3/4 or 8.8 rearend, or are those the same?

With everyone's help I figure I have a 3.78 or a 3.89 stock gear in my '56 ford. I need to get a tach but I know it's running too high rpm's on the highway (converted from 292 3 speed man to a 302/c4). I'll convert to AOD down the road, but for a quick fix I'd like to replace the gear to a 3.08. A 9 in rear would be my preference but my stock was modified for c noch and bags (see my pic).

So when looking for a new ring and pinion, do I look at 8 3/4 or 8.8? Thanks everyone, this is my 1st ford in a ford.

 

I don't think either one of those would work. To the best of my recollection, the 56 and older Ford rears were an animal all to themselves. Certainly not the 8.8 of later years and not the 8 inch that came out in Mustangs and Falcons. The 9inch came out in 57 so thats no help either.

 

Thanks Don!

 

If memory serves me correctly. 52 thru 56 Ford and Merc rear center sections all exchanged. Except for wagons, T-Birds and "heavy duty" cars. (which used Dana 8.8 rears)Try getting a center from a car with an automatic.

 

The '49-'56 Fords all used a Spicer type diff that didn't have a drop out center section. They don't share anything in common with a current 8.8, and an 8 3/4 is a Chrysler rear from the sixties and seventies. I don't believe you will find too much in the way of lower numeric gears (higher ratio) for your differential, and if your is in good shape it might be a better deal to do the AOD sooner than later.

The other end of this deal is that most of the current stuff in wrecking yard that you could use comes from overdrive equipped cars these days, so the common ratios will be very close to what you have. I know the Ganada 8" used to be a fairly good swap in your car, and could net ratios in the 2.80 - 3.00 range if you can find one.

 

Thanks for the advice, I may just go with the AOD now.

 

Ford had two rear axles 49-56; the 'standard' Hotchkiss (drop-out center) that was used in most passenger cars, and the heavier-duty Spicer in station wagons, sedan deliveries, Police models, and T-birds. The automatic cars got either 3.22 or 3.55 gears, the stick cars got 3.78 (non-OD V8), 3.89 (OD V8, non-OD six), or 4.11 (OD six). Very few later parts interchange.

If any of the original paint is left on the third member, the 3.22 were gray, the 3.55 red, and the rest were black.

 

Depending on what year your engine is, to make an AOD work you will have to get the right flex plate for the combo. Ford changed the balance weights on the small blocks some time in the early eighties, and bolting an AOD to say a '78 small block with the flex plate that originally came with the trans spells disaster. Been there done that. I just dug through some small block Ford books until I came up with the answer I needed, but if you need a hand I'll help if I can. The AOD will be the best money you have spent on your car by the time all is said and done.

 

Do the AOD swap you will be glad you did you want to look for a 1988-93 donor AOD these had the later lubrication upgrades and improved valve body and are still non-computer units,pass on 1987 or earlier AOD's.I have an AOD in my '54 pm me if you need more info about the swap.

 

Thanks! I'm somewhat new to Tucson so I'm building connections. I'll probably go with the AOD. As Jeff also noted below, I just need to make sure I get the right one.

 

Thanks Jeff, I appreciate it! I'm in Tucson and I'm missing out on some good shows in Phoenix, hopefully I come across a good deal on the right AOD that will not give me a headache. I found a calculator on the ring and pinion page on Summit and based on my tire diammeter, 75 mph, 3.78 stock gear, I could be looking at 3,600 rpm. That's not going to work for a 1.5 hr trip to Phoenix.

 

With the AOD's .67 overdrive your RPM's would come out at 2412, big improvement!