What Differential Do You Have in Your 1965 Barracuda?

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No wonder why you got what ever they wanted to put in your car when it was built. I have never heard any logical explanation why there is no code differences between the 7 1/4 and 8 3/4 rears in 66. Here is a page from the "Ordering information" from Chrysler Corp. Now in 66 were all open rears 7 1/4 and all Sure Grips were 8 3/4? It doesn't say and you should have been able to get either rear axle with a SG or open.

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toolmanmike said:
741 and 742 came first. 741 cases were used in the A bodies and 742 in the B bodies.
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However, there was another at least one interchangeable 8.75" that predated both of those, I believe my Dad's 59 Chrysler wagon had one, and it was common, so did my 62 Dart.
Oddly I see no 2.76 offerings.
 
My 66 formula S, 4 speed came with a 7 1/4 sure grip. My 67 Formula S, 4 speed came with an 8 3/4 sure grip 741 case. Both came with 3.23 gears.
 
J-c-c said:
However, there was another at least one interchangeable 8.75" that predated both of those, I believe my Dad's 59 Chrysler wagon had one, and it was common, so did my 62 Dart.
Oddly I see no 2.76 offerings.
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ANd I juste deleted my link tab. Yes, 8 3/4 rears started in the 50's. I was talking about the A and B body rears of the mid 60's.
 
cosgig said:
The 8 3/4” was available by late 1965, although always as an extra cost option. Mopars big fix for the weakness was to make the 7 1/4” Suregrip standard on the 4bbl cars. I would bet that under warranty, the 8 3/4” was not the first repair, it was probably given to repeat “offenders”, after a couple times into the dealership.
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My 65 Barracuda, which I've owned since August of 68 when it had 35,000 miles on it, was originally a Commando 273 4 speed. It had a 3.23 open 7 1/4 rear (no sure grip).

The original 7 1/4 rear lasted 90,000 miles (long out of warranty). Replaced it with a junkyard 7 1/4 that lasted 20-30,000 miles. Replaced that with an 8 3/4, some time in the early seventies.
 
YY1 said:
Actually 741 was used in 66 B body cars as well.

742 was an interim design from about 1969 to IIRC early 1970.

Then the 489 came in.

WAY more 742 and 489 cases made than 742.
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My 67 Hemi Charger (automatic) came with an 8 3/4 rear with a 742 chunk.

The rear in my 64 Polara convertible when I got it was a tapered-axle 8 3/4. It had a 742 chunk with 2.76 gears. But I have to say that was probably not the original chunk because a 383 4-barrel Polara in 64 would have had 3.23 gears standard. (It has a 66 Charger 8 3/4 rear in it now, with the original 3.23 sure grip 742 chunk out of my 67 Charger.)
 
Going by the casting numbers, IMO, the 741 and 742 third members both started around 1960 plus or minus a year or two. Which one the car got was mostly dependent on how much horsepower the car was going to have and/or if it had a tow package or some other heavy duty use. As for when it was first available from the factory in an A-body, I still haven't seen a documented '65 model with one. I have an early '66 (8/17/65) with a 273/4 and a 4 speed with one, but, I've seen other '66's with the same drivetrain and a factory 7 1/4 sure grip too.
 
4mulas said:
I had one of the very first 1966 production formula S car’s, number 00521 of the assembly line built in September of 1965, and it came with a suregrip 3.23 ratio 7 1/4" diff. I Think that it could have come with a 8.75 if a box was ticked or if they weren’t trying to use up 7.25 sure grip units.

most of if not all later production S cars for the 66 year received 8.75" units
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Mine is #499 (Aug 17, 1965) from the Hamtramck plant and has an 8 3/4 behind a 273/4 and an 833. Where was yours first sold? Mine is an original Hawaii car. I've been looking for an earlier '66 Barracuda for over 40 years now and still haven't found one. Yours is the closest however, even though I would have thought it would have been an August build with that number. Maybe yours is an LA plant car?
 
cudamark said:
Mine is #499 (Aug 17, 1965) from the Hamtramck plant and has an 8 3/4 behind a 273/4 and an 833. Where was yours first sold? Mine is an original Hawaii car. I've been looking for an earlier '66 Barracuda for over 40 years now and still haven't found one. Yours is the closest however, even though I would have thought it would have been an August build with that number. Maybe yours is an LA plant car?
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It was sold new in California. I believe Santa Rosa. Also was a, obviously 273 commando, but auto on the column and factory A/C car. Light mauve metallic with factory stripe (I didn’t put that on after I restored/painted it) and black interior. I put rallye’s in it for fun but in retrospect I preferred the 14" S wheel covers….

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Nice! Was it built at the LA plant? It should have had the "V" emblems front and rear too, before they came out with the fish ones. Mine even had the "V" horn button too. I don't know about the wheel covers as mine had mags on it when I bought it in 1980.
 
Of the 20+ '66 Barracudas I've had, I also had one that color, but, none of any of them had the factory racing stripe! I did have two vinyl top cars though, which are fairly rare. One was a FS with A/C. I had most of the available colors, except black and white, or special order color. Probably more silver ones than anything.....still have two. Several green and yellow ones, one red, one dark red (looked maroon), tan, citron, etc.
 
cudamark said:
Nice! Was it built at the LA plant? It should have had the "V" emblems front and rear too, before they came out with the fish ones. Mine even had the "V" horn button too. I don't know about the wheel covers as mine had mags on it when I bought it in 1980.
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It did, front and rear. The grill centers were also steel, the early ones were, later they switched to aluminum (or vice versa, can’t remember right now). This one also had a factory woodgrain steering wheel. Power steering manual brake car. Factory drums, but I switched the front to Kelsey Hayes 4 piston
 
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toolmanmike said:
Yes. 7 1/4 was stock. If you blew it out (with the Charger/Commando engine) you got a 8 3/4. Or so I've heard
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Yes, about mid production year dealers were experiencing blown rear coming in under warranty. Almost all were 4speed commando cars. MaMopar relented and sent out a message to the dealers that under warranty replace the 7.25 to 8.5 when available. Following that NHRA changed the rules for stock/Super Stock and allowed the 4speed cars to run the 8.5. I’ve posted copies of those letters off and on over the years. I’ll have to dig them up again.
 
from personal experience, i had a 65 dart, with 235/273, four speed car, dealer replaced 3 sets of gears in 7 1/4 , i changed to 8 3/4 then, a friend had a 65 cuda, same power train, he went through 11 7 1/4 rear ends, dealer told him no more free rearends, he had to change to a 8 3/4 rear end. i have the original letter from nhra, about the 8 3/4 in 65 a bodies, dated aug 1965, allowing 8 3/4 rear end usage . just food for thought
 
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