741 rear end

[Russ69Runner]

Got mine on the table. Checked the ratio stamped on the ring gear. It read's 2.76 ratio. Have counted tooth on the ring gear and it come's in at 47 tooth. The date on the ring gear is 11-19-68. But the casting on the chunk is RR-70 also has the 741 on the same side behind where pinion yoke is. So all I see is the 3.55 or 391. gear set for sale. What the heck have I got and what ratio should be used with the 383 and four speed set up. Will have A/C.

 

[quikbird]

Gear ratio depends on purpose you want to use the car. If not racing probably 3.23, or 3.55's

 

[dmartin]

I have the granny 2.76 Highway gear gets a little better gas mileage

 

[69hemibeep]

I don't think the RR70 is a date. The 741 chunk was the earliest of the 8 3/4s. 276 ratio will go down the highway nice

 

[Russ69Runner]

Ok. I don't see it for sale the 2.76 ratio. So the next one up is the 3.55 if I am not wrong. Appreciate the info. Will look to see if I can find the original gear set up if not then the 3.55 would be the next choice.

 

[69hemibeep]

Allot of them got 3.23s what do you want the car to do?

 

[Russ69Runner]

Yea that is what I read. Can't find it for a 471. Can find 3.55. Would like it to preform like it did from the factory. So guess I am stuck with the 3.55 ratio. Thanks Bob if you have any other idea's where to get the 3.23 set from would appreciate it. Russ.

 

[quikbird]

dts in Detroit, Randy's ring and pinion for a couple

 

[Basketcase]

3.23s are a nice all around gear, nice take off, and pretty good mileage. My last car had 3.55s, alotta fun, plenty on take off while still decent mileage, that car loved to cruise at 70. The one before that had 3.91s, LOTTA fun, but high revving at 60.

 

[droptop]

741 has the small pinion. You should have a 489 case originally, especially with a 4 speed. :2cents:

 

[69hemibeep]

I wouldn't use a 741 in a b-body unless it was an auto and an open diff

 

[Russ69Runner]

This car was a four speed car. Someone swapped the trannie. for an automatic 727. I will not be drag racing this car but you know with the power might have to burn some rubber. Like I have said before if I want to drag will buy a car and fix it up just for that purpose. Would not go through all the body work and total restore for a drag car. Thank you all for the input. Will do some calling around and get more advice form the supplier's.

 

[RKNRLR]

got 3.55's in mine, was cruising at about 3000 at 60mph, just put some taller rubber on and now she's at about 2850 @ 60