Rear end identification...

[POPS6T6]

Is there any way to find out which rear end this is? Seems that the numbers on the side are a number 7 and beneath that 207074 and beneath that 24 and the letter A and there is also an X up to there. I can't get under the car right now and these were the best pics I have.. I'm just wondering if there is a way to determine what this is so I can begin looking at what rebuild kit I will need for this...

 

[Oklacarcollecto]

207074 look for a 1 one the right side of the numbers. 2070741 would mean it is a 741 case in an 8 3/4 rear end.

 

[rally]

look like 741 8 3/4

 

[POPS6T6]

207074 look for a 1 one the right side of the numbers. 2070741 would mean it is a 741 case in an 8 3/4 rear end.

I zoomed in on the pitcure and I think you are right, there does appear to be a one there also. Thanks so much! Wasn't sure which case it was, and to be honest, not sure if 741 is good or??? It was on the donor car when I bought it and planning on dropping it soon and rebuilding it and or replacing gaskets, whatever is neccessary..

 

[1970Duster]

look like 741 8 3/4

X2 it is a 741

 

[POPS6T6]

I zoomed in on the pitcure and I think you are right, there does appear to be a one there also. Thanks so much! Wasn't sure which case it was, and to be honest, not sure if 741 is good or??? It was on the donor car when I bought it and planning on dropping it soon and rebuilding it and or replacing gaskets, whatever is neccessary..

Well I found this website http://members.tripod.com/mojo_page/chry875.htm
and it breaks them down pretty good. "1-3/8" small stem pinion (aka. '741')
Carrier casting numbers: 1820657 (1957-1964), 2070741 (1964-1972).
This assembly was typically used in low weight/low horsepower applications through low weight/medium horsepower and high weight/low horsepower applications.
Pinion depth and bearing preload is set with shims. "

Now I wonder if I that will work with my drivetrain, 360 and 727 transmission right around 400hp? Or is it possible to put a bigger case on that rear, and if so, would that also mean new axles and so forth?

 

[wish4hemi]

The 741 case will be fine. Everybody always freaks out when they see that it was intended for "low weight/low horsepower" stuff. I've beat the crap out of one in a '70 Charger 440/727 and never had any problems in 20+ years. I wouldn't hesitate the slightest to put a 741 case in a 500+ horse street car. Good luck trying to break it.

 

[POPS6T6]

The 741 case will be fine. Everybody always freaks out when they see that it was intended for "low weight/low horsepower" stuff. I've beat the crap out of one in a '70 Charger 440/727 and never had any problems in 20+ years. I wouldn't hesitate the slightest to put a 741 case in a 500+ horse street car. Good luck trying to break it.

Well I'll do my best! Thanks for the input, being a novice and all, I def did wonder when I read that..

 

[cosgig]

Did I happen to tell you about the 68 Roadrunner 383 4 speed car I parted out?? Coded for heavy duty EVERYTHING, except... you guessed it, a 741 case open rear!!! Go figure!! Geof

 

[64ValiantConv]

Yeah, I always get a kick out of folks downing the smaller pinion 741. It helps keep the 741 affordable.

The smallest 'weakest' 8 3/4 pinion at 1 3/8 (1.375") is bigger than the Ford 9" pinion at 1.313".

 

[805moparkid]

Yeah, I always get a kick out of folks downing the smaller pinion 741. It helps keep the 741 affordable.

The smallest 'weakest' 8 3/4 pinion at 1 3/8 (1.375") is bigger than the Ford 9" pinion at 1.313".

and dana 60...

as everyone knows the problem with a drop out is ring gear deflection anyways...

 

[demon seed]

Yeah, I always get a kick out of folks downing the smaller pinion 741. It helps keep the 741 affordable.

The smallest 'weakest' 8 3/4 pinion at 1 3/8 (1.375") is bigger than the Ford 9" pinion at 1.313".

Of the three 8 3/4" the 741 is the only pinion without a stress riser on the shaft.

 

[4spdragtop]

Of the three 8 3/4" the 741 is the only pinion without a stress riser on the shaft.

Hey Terry, whats a stress riser?

 

[demon seed]

Hey Terry, whats a stress riser?

When I get stressed out my temper rises to the blow off point and I go boom:-k:angry5:

No okay, when you're talking shafts, whenever you change the diameter of a shaft from one dimension to another (either smaller or larger) that point of intersection becomes a stress point. If something were to come along and smoke that shaft in all likelyhood it would break at that point. The 489 pinion necks down from the large support bearing to the small but the 742 is very pronounced with an actual machined 90deg shoulder. The 741's shaft is almost the same dia from bearing to bearing. I'm not saying a person will ever break an 8 3/4" pinion shaft but the weakness is there. Myself I've never seen one break there, I have seen them snap off up at the yoke spline. This is also very important to crankshaft rebuilders if they've done any resurfacing or machining on the main journal or rod throw. Before their job is complete they must insure that the fillet is the right contour and chamfered properly or snapola she'll go.

-------------489------------741--------------742