swinger1969
Repeat Mopar guy
How can I tell which rearend casing I have in my 69 Swinger 340...741 or 742? I'm told it's on the VIN tag but can't decipher it . Do they both take the same crown & pinion ?
Thanks Folks, I'll check it out .Crawl under the left side and get the numbers off the nose of the third member. After all these years there is no telling what’s in there.
Well damn ! Just looked and the marking on the case says 2070741. That REALLY sucks because I have a set of 3:55's I was going to put in in place of the 3:23 and they're for the 489 case !741 small pinion.(Straight shaft)
742 Larger pinion (Straight shaft)
489 Large pinion (Tapered shaft) Most consider the strongest in 8 3/4 rearend.
Ok thanks !Very few A-bodies equipped with an 8.75" rear did not get a 741 casting.
Before I sell off the new 3:55's , are the casings interchangable? Could I swap the 741 for a 489? Just wondering what my options are here - being up in Canada it would cost a LOT to send them back then reorder etc.Very few A-bodies equipped with an 8.75" rear did not get a 741 casting.
I really appreciate the help! When I bought the gears from Summit I bought the installation kit as well , so the bearings etc are there. I'm pretty sure the diff in it is a sure grip .Yes you can buy a 489 case and bearing kit and use your gears. If your original 741 is a SG, you can use that SG in the 489 case.
I bought the C&P from Summit as well as the installation kit , so I guess I just need a 489 case. The yoke will be different because apparently the 741 has a tapered shaft and the 489 has a straight shaft.Any case will bolt into you housing but each case takes its own gearset. Differentials will go into any case . Check the spline on your new gears to make sure you have the correct yoke when the time comes .
741 has a tapered shaft and the 489 has a straight shaft.
Sorry , that's what I meant to say .Re read post 8. 489 is tapered shaft .