Rearend Dilema

[old-school]

OK,
I need some input. Here's my current situation. Last year i had a guy help me replace the 4:10's in my 742 case with 3:55's. Well the gears whine terribly and i can no longer stand it. Obviously he messed up on the pinion depth or backlash or whatever. Regardless, it's water under the bridge now, so to move on to my current issue.
I love the 3:55's. I hated the 4:10's. Don't get me wrong, the 4:10's were awesome coming out of the whole but taking any kind of drive down the freeway was mind blowing.

I found that the 3:55's gave me the best of both worlds as long as i don't cruise over 65mph. Since my tach doesn't work, i could feel at 65mph that this was ok, or at least it felt ok to me. It's the whining that i can't take anymore. It's driving me crazy. Well, after speaking with Cass (DR Diff), a very nice guy, i was informed that i can no longer buy 3:55's in the 10 spline ring and pinion. I already have a local gear shop here in Indy ready to put the new gears in when i buy them. I'll drop the center section myself and just take it in to them. At $250 for the install and proper depth and backlash settings, the peace of mind that when i get it back home and throw the center section back in that they won't whine, i feel like that is a good deal.

Cass only has the 29 spline 3:55's and my setup is the 10 spline. He says that it will be at least a year before US Gears probably gets around to producing 10 spline, if they do. So, then he informs me that 3:23 isn't made anymore either! All he has that will work for me in my 742 is 3:73's. I have to do something before the summer gets here. There just isn't very much information from Mopar guys regarding 3:73's and how they perform as far as highway driving etc., I know when i changed the 4;10's to the 3:55's, i loved the improvement in gas mileage. I'm driving a 73 Challenger with a 440CI, 727 manual valve body tranny, three speed slapstick setup. My rear tires are 235/55/R17 and they are in too good of shape right now to go out and buy taller tires.
 
According to the visual speed, rpm calculator, with my tires and 3:73 gears at 70 mph my rpms are 3273 and at 65 mph my rpm's are 2996. Will this be ok for let's say a 6 hr drive on the interstate or am i pushing things. I need opinions Thanks in advance everybody.

http://i553.photobucket.com/albums/jj380/old-school1960/73challenger007.jpg

[Moparal]

so whats wrong with getting a 29 spline yoke?  They are cheap enough to find. I have some 10 and 29 here as well

[old-school]

Ok,

Just let me make sure i understand this. If i buy the 29 spline 3:55 ring and pinion set from Cass, then all i have to do is buy a 29 spline yoke to go with it and it will work with my setup in my 742? Will the 29 spline yoke work with my u-joint on the car? Or do the 29 spline yokes only come in a certain size forcing me to get a different drive shaft etc.,? Learning as i go here. Thanks

[old-school]

Another question i have regarding rearend gears. Would it be wise to try and attempt to buy used gears that look good to put in or would they be worn to where if they didn't match perfectly that they would whine? I was told by the guy who built my car that the 4:10's in my car were new gears. I know they look great and i would be willing to trade them to someone for a equally great looking set of 3:23's that would work in my 742 case. But if using used gears would make noise, then i'd be back to square one.

[Moparal]

Ok,

Just let me make sure i understand this. If i buy the 29 spline 3:55 ring and pinion set from Cass, then all i have to do is buy a 29 spline yoke to go with it and it will work with my setup in my 742? Will the 29 spline yoke work with my u-joint on the car? Or do the 29 spline yokes only come in a certain size forcing me to get a different drive shaft etc.,? Learning as i go here. Thanks

By the 29 spline and buy the yoke, they will work and no new driveshaft required

[old-school]

Moparal, 

I just located new Yukon 3:55 10 spline ring and pinion for $219

Are Yukon gears good gears and is that a good price?
Thanks

[old-school]

Now i can't get the Yukon 3:55's but i can get Nitro 3:55's

Can anybody tell me anything about Nitro Gears before i pull the trigger and buy these? Thanks

[Moparal]

yukon is ok , but shop around for a price 50 bucks cheaper.  The gears are out there. Just be patient and save some money