Found a possible donor axle for lbp swap. It's in a 73 dart with a 318 and automatic has 10" rear drums any idea on gear ratio also.

Could be large bolt pattern 7 1/4 or it could be an 8 1/4. Ratio is likely 2.76 unless it's an 8 1/4 and then it may be 2.45. Are you certain it's large bolt pattern? Plenty of drum brake 1973 cars.

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Joshua

If unmolested there should be a metal tag showing the ratio. Maybe it will also have SG on it! If it is a drum front really good chance it is SBP. I have a 74 slant Dart that's SBP.

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'72 Duster 198 stock cam, 3:23's

93 D350 Cummins THD Maxfuel 35mpg parts to hit 400hp+ Suncoast Cat2 A518, converter DDP Stage III injectors 62/64 HX35, 3 piece manifold, 4" Diamond Eye, Gear Venders OD. Stage I street/tow PDD head on order.

Were any A-bodies ever made that were 4-wheel drums with 10" rear drums?. I've seen 9" or 10" front drums, but rears on both were 9". I'd expect A-body with 10" rear drums to have front discs, which for 73-on was of course lbp.

Assuming OP was correct on drum size, then yes, it could be 7-1/4 (direct bolt-in, might have to play games with the parking brake cables- or not), or 8-1/4( need driveshaft work in addition to pkg cables) As Joshua stated, the default ratios for both were pretty numerically low.

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63 Valiant Wagon
225 - 4 bbl

My '66 Barracuda was 10" drum at all 4 corners. I believe CJ's '74 Valiant was the same way.

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Joshua

I am pretty sure its a lbp 8.25. The cover was more of an oval shaped than my previous 7.25s. Yes its was a disk brake front end car. Just to late.

So I need to pull the drive shaft and spring pads correct?

10 bolt cover is an 8 1/4. Get the shock mounts/spring plates. The driveshaft only works if it's the proper length. I don't know what wheelbase the donor is as you haven't said if it's a Dart or Dart Sport nor do I know the wheelbase of the recipient. Regardless the driveshaft needs to be 1.6" shorter if you're going from a 7 1/4 to an 8 1/4.

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Joshua