8 3/4 rear end.

[Russ69Runner]

Hello guy's. Here is the question. I have a 383 with a four speed wondering what would be the factory ratio for the rear end. My ring gear a pinon are sloppy. Know will have to rebuild it so what is the best ratio for my 69 runner. Know 4.11 dose not get good gas millage. Russ.

 

[ACME A12]

Most likely 3.23 to 1. FT and/or build sheet should tell you what it came with. 3.55 or 3.91 would have been optional.

 

[Russ69Runner]

Thanks ACME A12. As you know I have no finder tag on this car or any build sheet. Know will be trying to get fuel economy. LOL. Just figured to put it back original as possible. What would the 3.55 or 3.91 do in respect to performance. Is their a number on the housing so I can tell what I have. Can't find any tag on the rear end is their a casting number to go on. Only finding ring and pinion set in classic for 741-742-489 housings. Figure the 489 is for Hemi may be wrong. Russ.

 

[droptop]

489 is what you should have. If you have a 22 inch radiator, you can count out 3.90 or higher numerical numbers as these required heavy duty cooling. (26 inch radiator) My guess is 3.55 gears in a 489 case.

 

[Russ69Runner]

I appreciate the info droptop. Going to look on the Rear end today and see if I can find any number's. If not then when it is apart will count the teeth on ring gear and pinion.

 

[quikbird]

just turn the drive shaft and count how many turns it takes for the rear wheel to rotate once. most rr's came with the 3.23 ratio. higher the number the quicker it accelerates but revs higher at highway speeds.not so gas efficient

 

[Russ69Runner]

Thanks Quikbird. Was kind of trying to see what it came with so when I rebuild it. This gives me something to go off. Still will put some kind of over drive in later to get the high end millage.