Thanks, memike...any idea where that diagram lives? (or what keywords to use to search for it?)
I just googled trying for that and hit on a thread on the HAMB that had weights for a Dana60 and Ford and GM rear-end:
HP Loss- Which Rear End Is Best
12 bolt 210lbs
S60 230 lbs
9 inch 238 lbs
Just thinking about my slant build - won't need that much strength (8 1/4 s/b fine)...how much lighter might it be? Give up the ability to quickly swap pigs to change gear ratios, but... These are all within 30 lbs of each other, so maybe it won't make that much difference regardless...
Anecdotally, from this Hemmings article, the 8 1/4 is much lighter:
http://www.hemmings.com/mus/stories/2007/01/01/hmn_feature21.html
Although not as strong as these other two units, they are reasonably easy to locate because Chrysler used them in a wide range of original applications and, secondly, this rear is much lighter than the Mopar 8 3/4-inch, without sacrificing strength.
and later in the same article:
Although lighter than the Chrysler 8 3/4-inch rear end, the 8 1/4-inch unit is heavier than some of the stock 7 1/4-inch Mopar 9-bolt assemblies it has been known to replace.
But, how much weight are we talking? 20 lbs? 100 lbs?
A guy on moparchat claims the 7 1/4 weighs 80 - 110 lbs less than an 8 3/4
7 1/4 rear end imrpovements? - Moparchat - Home of MOPAR enthusiasts worldwide!
"The weak link is the spider gears and parts listed above. The only real 'beef up' you can do is add a sure grip. This will help devide the load between the spiders, axles, etc. As you know, new ones aren't available. To make the problem worse, used ones are very hard to come by. Some of the axle seals are getting scarce also. This is too bad, they are 80-110lbs lighter than an 8 3/4, too bad sure grips, spools, better axles and gears aren't available. It would be a great rear for the lower HP cars.
Bottom line, and you've already heard this, upgrade to a 8 1/4 or 8 3/4 rear, they also come with a bigger brake.
But if you really want to keep the 7 1/4, don't put more the 250HP to it and/or stock up on some spares, they're cheap."
