7 1/4 to 8 1/4..... easy?

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Firemybird

Firemybird

Firemybird
Joined
Jul 18, 2008
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Riverside, CA!!!!
Well i fryed my spider gears on the ol' swinger....

It is a 7 1/4 rear at the moment (turned by a stock 318/727)....

I found a 8 1/4 at a scrap yard in another swinger (same year) for $260 out the door.... But i dont know if it's gonna require modification in order for it to bolt up....

i did some measurements and they are both the same length backing plate to backing plate (50" give or take)but the 8 1/4 sit's back a little farther than my 7 1/4 (closer to the gas tank) and it's also 4" longer from the inspection plate to the u-joint yoke.... will i have to modify anything in order to squeeze this bad boy in there? do i need a u-joint conversion kit? I need to do this tomorrow so any help would be GREATLY appreciated, thanks!!

Alex.......
 
Sounds like you'll need the donors driveshaft too.
 
I swapped an A-body 8.25 for the 7.25" I had. I had to shorten the drive shaft about 1.5". The doner car is likely a 904 and your 727 is longer so you will likely need to shorten the drive shaft. Its pretty inexpensive cost me $75 to cut balance and install new u-joints at the local driveline shop.

If you can get the shock plates that is the best situation but you can easily elongate the holes in the 7.25" to accept the 3" u-bolts. Most likely you won't get all 4 u-bolts intact, new ones are about $5 each at the local NAPA.

The yoke on the 8.25 will be the same as the 7.25 so no need for a conversion joint.
 
All 4 u-bolts are there and intact, it's in pretty good condition, gear oil was clean with no shavings, almost look's freshly rebuilt.... DAMN if i only had that drive shaft..... how can you tell if your tranny is a 904 or a 727, i was told by the previous owner that he "thinks" it's a 727 but he's not a very reliable source of information.......
If i do need to get it cut there's a place that my shop has an account with called "Ed Moore Drivelines" and he seems to know his stuff....
 
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