can any 1 tell me what kind of gears these are?

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360-68cudu

360-68cudu

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I found these gears on a old dodge 1962 pick up. No tag just this what do you guys think?
 

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How do i go about that is it imprinted in there? Or is there a special way to check.
 
Its an 8-3/4 rear with a 741 case.....To check ratio, easiest way is put a mark on the drive shaft and a mark on the tire.....jack up rear wheels if sure-grip and spin tire one revolution and watch how many times drive shaft spins....3-1/2 time is 3:55 , 3-1/4 turns in 3:21....etc. etc...If you jack it up with both wheels off the ground and the one tire spins in the opposite direction when you turn it, it is an open rear.....And you can still check it to see what gears on in the rear by using the same method as described above, however one tire must be on the ground when checking.....So only have one tire in the air....
 
360-68cudu said:
How do i go about that is it imprinted in there? Or is there a special way to check.
Click to expand...

Yup...it's stamped into the ring gear, along with the part number, date code,etc......

attachment.php
 
Small pinion, 8.75.
Most likely a 3.91 ratio.
If it has a nut on the end of the axle keep looking for a newer pumpkin, the axle splines may be different than the newer ones.
 
Gears are interchangeable, 741 is decent for "light/light" (weight/horsepower) platform, tapered axles are no good. Supposedly if the drain plug is painted its a SG (myth?) may still have a ratio tag on a bolt?
 
bbrroowwnn said:
Its an 8-3/4 rear with a 741 case.....To check ratio, easiest way is put a mark on the drive shaft and a mark on the tire.....jack up rear wheels if sure-grip and spin tire one revolution and watch how many times drive shaft spins....3-1/2 time is 3:55 , 3-1/4 turns in 3:21....etc. etc...If you jack it up with both wheels off the ground and the one tire spins in the opposite direction when you turn it, it is an open rear.....And you can still check it to see what gears on in the rear by using the same method as described above, however one tire must be on the ground when checking.....So only have one tire in the air....
Click to expand...

I didn't know it was that easy thanks but unfortunately this truck is jacked up on welded on to some old rim stands is there an alternative way to check? I know there limited slip I'm hoping there 3.55 or up. ( I wish they were posi but there not)
 
pishta said:
Gears are interchangeable, 741 is decent for "light/light" (weight/horsepower) platform, tapered axles are no good. Supposedly if the drain plug is painted its a SG (myth?) may still have a ratio tag on a bolt?
Click to expand...

What are my other options using 8 3/4.? Other than the 741?
 
742, 489 case
742 uses a clutch type sure grip.
489 uses a cone type sure grip.

489 has the largest pinion, but a 742 is equally as strong. Like comparing apples to apples.

I prefer the 489 cone style but this is just my opinion.
 
360-68cudu said:
I didn't know it was that easy thanks but unfortunately this truck is jacked up on welded on to some old rim stands is there an alternative way to check? I know there limited slip I'm hoping there 3.55 or up. ( I wish they were posi but there not)
Click to expand...


Another way that works, especially if the ring gear doesn't have the ratio stamped on it, is to divide the amount of teeth on the ring gear by the amount of teeth on the pinion gear.....that also tells you the ratio, unfortunately you have to pull the chunk out to see that also....
 
65Val said:
*742 and *489...1 3/4" straight stem and 1 7/8" tapered stem respectfully.
Click to expand...

So my pic shows 2070-741. The 741 at the end means there 741 do 742 and 489 read the same? And do the 2070 # mean anything important?
 
bbrroowwnn said:
Another way that works, especially if the ring gear doesn't have the ratio stamped on it, is to divide the amount of teeth on the ring gear by the amount of teeth on the pinion gear.....that also tells you the ratio, unfortunately you have to pull the chunk out to see that also....
Click to expand...

My dad was trying to explain this to me but he couldn't remember the exact way to calculate. Thanks
 
The last three numbers are the case numbers.
741,742,489
 
360-68cudu said:
I didn't know it was that easy thanks but unfortunately this truck is jacked up on welded on to some old rim stands is there an alternative way to check? I know there limited slip I'm hoping there 3.55 or up. ( I wish they were posi but there not)
Click to expand...

The differential is neither limited slip or posi. Those are names related to rear ends other than Chrysler rears. If it has clutches and both wheels turn in the same direction when you spin the driveshaft it is a sure grip (the Chrysler name for what other people refer to as limited slip or posi trac(gm term)). If not it is an open rear end. The names above are all just different names for a differential that has clutches and prevents one tire from slipping or spinning. There are three types of differentials - open (no clutches), sure grip (or posi or limited slip or locker or whatever) and a spool - not really a differential, both axles are permanently locked together, and only for race use.
 
I have a 3.54 gear set from 1959 marked just like that. so it started before 1960 .Lawrence
 
gear cases up to about 65 had the ratio stamped on bottom side of case, on a 'flat' area.
not sure it would change my idea to buy the gears either way, suregrip 3.55 or 3.91. got to do it
 
sometimes on them old trucks they put a sticker under the hood or the drivers door jam.telling you the motor size and gear ratio.if its a six cylinder it cold be a lower ratio like 323 355 or 391s...........Artie
 
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