8 3/4 Pumpkin Swap Question

[Merlin]

I have an 8 3/4 (not sure grip) in a bone stock 71 340 Duster--casting 2881489. I have a friend with a sure grip "741" casting. Will my drive shaft from the 489 bolt right onto to the 741? I'm not sure if the U-joints from a 489 drive shaft setup are the same as a 741 drive shaft setup. ? Is this a smart swap?

[JCFcuda]

Yes it will, Sure why not.Some say the 741 is weaker I dont think thats the case.
Jim

[rumblefish360]

There is sometimes a U-joint size issue. Lakewood has the fix with a special joint. 1 side is wide and the other side small. The swap is cake. All later 8 3/4 center seections are the same length.

[pishta]

It is smart if the 741 is good to go and the right ratio for you. Bad if you want to change the ratio, there are very few gear sets for the small pinion 741 out there. Better swap would be the sure grip out of the 741 into the 489 case, more gears available and it is a stronger case due to the fact that the pinion shaft is thicker.

[NUC]

I just did the same swap in my Bee. Original rear end was trashed so a non posi 741 unit was installed. I swaped it back out for a posi 489 case and to solve the u-joint issue I swapped the yoke off the old case. Fit no problem works great. The 489 case I had bought used large u-joints in it's yoke. My car used smaller joints in the drive shaft.