Third member swap between cars.

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HD539

FABO Gold Member
FABO Gold Member
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Maybe a dumb question but I have a third member out of my roadrunner that I’d like to put in this Duster. Both have 8 3/4 rear ends and are automatics. Does it swap in without modifications?
 
Yes, it would be a straight swap unless one has a spool and needs green bearings.
 
Yoke size?
7260
7290
1330
All stock possibilities

Then the 1350 is a common replacement.
 
U joint size may be different. But they make a cross over joint that has small and large caps to install a small drive shaft on a large yoke rear and vise versa
 
yes, they make a u-joint to adapt to any combo you may encounter. Good chance you may not even need to swap the u-joint
 
You never mentioned the gear ratios but depending how different they are you may want to change the speedometer pinion gear in the trans to get a truer reading on the dash. The difference is usually not much but a GPS or the one on your phone can help you determine how much it is out and decide whether the difference is worth the trouble. I always check it so at least I know if it is up or down from what it should be.

There's a couple of charts in one of the stickies for this forum that should help if you decide you need to change the speedometer pinion gear: Speedometer Gear Charts - Clarification/Differences
 
I hear of guys driving to the track and then swapping in a 4.88 pig in the pits. Man, that's alot of work on your back!
 
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