8.75 Axle - 741 / 742 / 489

KosmicKuda said
I respectfully disagree. The proof is my 69 A56 4 speed 'cuda 340 that has the original rear end and it's definitely a 489 case w/ factory 3.91 ratio. (built 6-13) This car has HD everything including front and rear torque boxes and a 15/16" diameter front sway bar. I think it was the combination of the gear ratio and 4 speed that triggered the extra HD stuff. Everything I ever read says the last model year for the 742 case was 1968. I don't have one in front of me but the 69 FSM probably does not have the 742 info in it.

All the 440 A-bodies were automatics. If Chrysler followed suit like on the Hemi and 440 B-bodies, it kinda makes sense. The standard rear in a Hemi or 440 car with an automatic trans was an 8-3/4. 4 speed Hemis and 440's automatically got the Dana.

I believe D5667 was agreeing with what I said in my quote below and if you notice I did say "nearly every 8-3/4 A-body left the factory with a 741 chunk".. Nearly (not every) being the key word, LOL... That was the great thing about ma Mopar. You never know what to expect. Yours being an example that Mopar did put some 489's in a-bodies. Like you said it was probably because of all the other HD pieces. Then again they might have ran out of 741's that day and just wanted to fill the order. That happened also. Even though 68 was the last year slated for using the 742 case the 69 FSM does include information on the 742 case and I have seen a few early 69 axles with a 742. My guess is they were just using up the 742's they had left over from 68 and thus included info on them in the FSM.

BTW: can I assume your Cuda is a formula S since it has all the HD suspension goodies?

fishy68 said
That's true. But an A-body is a light body Mopar. And the 383, while being a great running engine wasn't a real high horsepower engine. If I'm not mistaken nearly every 8-3/4 A-body left the factory with a 741 chunk, even the 69 440 cars which were high horsepower. I guess you'd have to call it the "A-body rule", LOL...