Rear Axle ID

[HellBelly]

I was curious as to what rear axle ratio I have.

The only things I see on the tag in regards to the rear axle is the following:

Rear Axle = 32
Rear Axle Cap = 3600
Make = Chrysler
Model = RF36

All my other trucks have the 3.55 or 3.94 in the "Rear Axle" area. What the hell is a 32??

[Red]

My guess would be a 3.23, the driver is misstamped and only says 32 rather than 3.23

[HellBelly]

Thanks Red!!

Now I'm ignorant on ratios etc..

I take it 3.23 is a better highway gear.

The 3.55 runs so much better than the 3.94 on the highway, will the 3.23 be even better?

[MountainMoparRobin]

Hellbelly
crawl under your truck and check the tag on the nuts of the rear axle and see what it says!
If it is a 3:23 then you'll have less rpms and higher speed, and better gas mileage.

[HellBelly]

I'll check that tag this weekend. Thanks!

[Hobcobble]

3:55's & 3:91's are the two most popular gears for the 8 3/4 MoPar axles
used in the Sweptlines. The 3:23's should give you better gas mileage
than the steeper gears. The differential tag, like Robin said, should be
fastened to one the pumpkin nuts. Your casing ID number is embossed on
the side of the diff housing [742 or 489 probably]. The "32" you found
most likely points to 3:23's. I run a 3:23 sure-grip in my R/T.... really
nice all-around gear.
John

[wideblock]

hey scott, is the truck a 4speed or 3speed? for the 3, you want a 3.55 or 3.91, the 3.23 and the 2.76 i have dont work that well with the steep split the 3spd has. the taller gears work good on a 4 speed due to the gears being split better. FYI smaller the number, the better it is on the freeway. heres what i used to decide on my gear ratios. this is straight from randys ring and pinion calculator, first is gear ratio, second is rpm at 75mph in top gear. 2.76=2244, 3.23=2626, 3.55=2886, 3.91=3178. as you can see, taller gears help a lot on the highway. i will be changing to a 3.23 shortly, the 2.76 and four speed works really good, but on the freeway, im not in my power range for the motor, so anything up hill really drags the truck down fast. but man is it the *#%^ on the flat ground. according to what i have read, a v-8 is best served between 2500 and 2800rpm at cruising speeds. right now i only get 2100 at 70mph, so it dont take a lot to bog the old girl down, but, due to the better gear split in the 4spd, i can hit 75 in 3rd if i wanted, and cruise 60. so all it takes to get up the hill is a gear change to 3rd till i hit the top. 3rd at 2800rpm and the truck doesnt even try to slow down going up hill. even with a 4300 pound car dragging behind it. i have a chart i made that has each gear at top speed if you are interested. 3spd and 4spd with each ratio i listed above showing the top speed each gear is capable of, or at least what you would get at 4000rpm out of the gear.

[Hobcobble]

I'm thinking that Scott is talking about his latest LA318/727 truck.
John

[HellBelly]

John,

That is correct, it's my 69 318/727

This weekend I'm going crawl under it and check that tag to make sure.

Sure Grip? Does anything signify this?

[Red]

some have a round tag around one of the third member bolts, or you could jack up the rear with the truck in park, and spin the rear wheel by hand, if its hard to turn, or the other wheel turns in the same direction, its a sure grip, if the other wheel rotates the opposite way, its an open rear end, or a worn out sure grip!

[cowboy]

I read on one off the site's , that a S in a circle , above the case # 's was a sure grip, , But my 3'91 both turn the same way , & no S in a circle , it's the 742 case , also scott the case #'s are on the driver's side of the pumpkin , the last 3 #'s are you case #'s 742 ect ect