rear end identification

[84IDI-BERTHA]

now this may be a silly question for you smarter guys, but im trying to learn from the best when it comes to IDI's so i came to you all. I am still young, trying to learn about these old trucks and one big question I have is how would I identify the rear end/gears on my truck?

is there a stamping on the steel or something? my question arose after i bought it from a local guy. older man, has a gooseneck in the bed and he used it for towing livestock trailers around the area. if i punch it on the highway to max speed, she will hit 70-75(if the speedo is right) and people like to honk and pass. haha. but after she hits 75mph range, she doesnt go anymore. that is all she has, but she is screaming like a damn freight train and the sound is quite nice

just my quick little bit, hoping to find out what it has underneath and if its possibly the reason she is so slow. i dont need it to go 110mph or anything, just want to learn

 

[mabc926]

There should be a gear tag on it, unless someone took it off.

 

[mabc926]

The gear tag should be on one of the bolts holding on the diff cover.

 

[84IDI-BERTHA]

sounds good to me. i should have looked underneath and it would have saved me the embarassment. haha. i appreciate ya. and as far as the gears go, is it a lower number (say 3.73s) is a smaller gear, thus turning faster giving it higher top end (for lack of better words) and say a larger gear in the 4's would be better for towing versus putting around?

 

[NTOLERANCE]

If the rear end is original, you may be able to check axle code on the door tag if its still there.

There is a guide on this site to decipher the axle code.

 

[84IDI-BERTHA]

ill definitely check it out. thanks guys

 

[gandalf]

Here's a site which might help you. It gives axle code translations, and toward the bottom it has visuals of the various axles and how to identify them.

Axle Information


From your description it sounds like you have 4.10 gears in the rear.

 

[RANOVRU]

Well a 250 IIRC wont have anything but a 10.25 sterling rear. More than likely with a C6 its probably 3.55's R&P, but a tag on the rear will tell for sure.

 

[Goofyexponent]

Are you running stock sized tires??

If the axle is the stock one,a s mentioned above the door tag will tell you, but the best way is with the gear tag. Even then, if someone swapped the R&P out, and put the tag back on...it won't be accurate.

How clean is the oil in the rearend? For a $10 tube of Black RTV silicone, and a gallon of new gear oil, you can be SURE what is in it and service the rear end at the same time.

 

[Kevin 007]

On the door tag, axle code 73 is a 3.54 Dana 70. Thats what mine is

 

[84IDI-BERTHA]

copy that kevin. i will check it out tonight when i get home. thanks.

Goofy- i am running stock tires. i will try to post pics in an album in the next day or two when im off work. im guessing for the worst on everything, this guy was around 80 i bought it from and had it since new. so being said, he took care of the truck but always expect the worse. i want to drain the rear end, coolant, brakes, etc. anything i can do to make it a happy girl. when i do end up servicing it i will have to look on here and get an idea how to do it. never have taken a rear end apart except for new oil. never serviced one.

 

[Dieselcrawler]

yep, 84 wont have a sterling unless it was swaped in. going to be a 70 or slight posibility of a 61. but doubtful.

 

[84IDI-BERTHA]

is there a certain rear end that is more desireable than the others? or is it just a preference for what you use the truck for? dont mean to beat a dead horse, but im new to all this. i love the older trucks as i grew up with them, but certain things i never did and would like to know for my own knowledge base

 

[Dieselcrawler]

many like the sterling due to the outboard drums. but they are all good. early sterlings had seal issues.

 

[84IDI-BERTHA]

again dumb question, but what are outboard drums?? i have noticed by just looking at the rear end that it seemed "internals" were protruding from the diff. instead of a nice round pumpkin it had squares and whatnot looking like they punched themselves into the metal.
are they better than inboard drums for any reason?