I am leaning toward using an overdrive 833 in my never-to-be-stock-again '63 Dart GT.

The engine is pretty dialed in with some nice port/valve work, full reciprocating rebuild, .40 block decked and a Comp Cam that seems to really like around 3000 to 3500. With the current 3.21 8 1/4 axle, the current 1972 date-code close ratio 833 is running a bit higher than that at freeway speeds, and the tall first gear is less than ideal for steep-hill San Francisco stop-and-go traffic. Also, I have zero plans to race.

Given all that info, I'm considering how to construct a trade offer for a '75 cast-iron case 833 OD I've located. The seller seems to think it's extremely valuable, so I don't want to offend him with a lowball; on the other hand, I don't want to give away my highly valuable transmission either! If I had the time (and cash flow) I'd just buy the OD and sell the 833 at my leisure, but that's not an option.

Any thoughts on the relative value of these two A-body transmissions ('72 close ratio and '75 cast-iron case OD)?

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Open the pod bay door, Hal.......

I don't like the ratio spread on the OD boxes with anything other than a stock camshaft. Once you raise and narrow the power band you want closer spaced gearing such as you have now. If it were my car I'd rather have the 3.09 1st gear 4 speed gear set that the '64-'65 cars had rather than the A833OD. A 5 speed would be even better.

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Joshua

I somewhat agree. A tighter ratio 5 speed with an Od 5th gear would be the best overall. But as a plug and play option the choice is limited on which way to go... Your Dart has the weight advantage of being lighter...the close ratio 4 speed and 3.21 is a pretty good combination. The OD has a pretty wide spread, but it does allow for nicer gearing. Although 3.09 1st is pretty granny, coupled with a 4.xx gear even a fat duster can climb the steep hills without a problem, but the rpm drop from 1st to 2nd will make you run the rpm high to keep the rpm drop in the power band on the upshift. With the OD you can still get good mileage with the "drag" gears (most like 3.55's for reasonable fun gearing and a moderate final ratio in OD).

I know of no comp cam that will raise and narrow the rpm band much at all, they are very mild, and even the Erson 280/270 raises the rpm band but the torque band has very little variation and the developed torque is much improved over the stock engines overall torque numbers over the normal driving range if the DCR matched the cam choice, it all depends on your goal and component choices. Even then with the OD and better gearing expect large rpm drop from 1st to 2nd (about 1000-1500), moderate drop from 2nd to 3rd(about 5-800), and about a 3-500 rpm drop from 3rd to OD...

The cast iron case OD is a weight disadvantage, but once rebuilt will take a lot of abuse compared to the aluminum case unit, the average price for he gear box alone is about $300-500 if plug and play, a little less if it needs rebuild (expect shop rebuild price to be be about $500, or closer to $250 if you can do it yourself and can do it yourself). The A-833 direct box goes for about $700-800 depending on condition.

Just some things to think about, I would not pay more than $300 for an A-833OD unless it has documentation of a complete and professional rebuild.

2 cents-

-D.Idiot

I got a non OD A-body iron 833 a few days ago for $100, but it is missing a shift fork. Last weekend I got an iron OD 833 at the pick N pull from an 82 D150 in condition unknown, but it also has the Hurst shifter.

The alloy case 833 can suffer from case wear from the unbushed countershaft, it is good to check for that, and make repairs as needed.

I think you will enjoy the non OD best, but its not a final choice as its easy to switch later. If you come across the Gear Vendors adapter for the 833 you might try that. Prices are all over, some sellers think they're rare. I see them in Chevy trucks too, get those for parts if the price is right.