The late A-body 7 1/4 does not need different shock plates. The axles tubes are still 2 1/2". The 7 1/4 is fine for most automatic equipped slant six street cars, but street/strip cars and manual trans cars driven aggressively can break them. My 318 equipped '77 LeBaron ate one. My 4-speed equipped '66 Dart ate one.

The Ford Granada/Mercury Monarch rear end is only about 1/2" wider per side than an A-body rear end and the Ford 8" is stronger and has better parts availability than the 7 1/4.

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Joshua

The Ford rear ends mentioned are good, but check the axle ratios. Granada/Monarch/Versailles rears often came with tall gearing. My son's car had a 2.47:1 ratio.
Also note that some of the Mavericks and Mustangs came with 4-lug wheels.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

There is also a 7.25" LBP rear from the same model years. Finding the 4.5" bolt pattern does not automatically mean you've found a 8.25".

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Interesting question. Would a '66 to '70 B-Body drum fit on the '73 A-Body drum brake spindle?