Another gearing question

[jteck10]

i currently have a 6" lift w/35s and stock (i believe) gearing. I'm wanting to upgrade to 37's in the future and curious what gears i would need
im thinking i get the gears in sooner rather than later to help the 35s along, and be ready for the 37s

with that being said, im curious how to tell if i have a 28 spline or 30 spline shaft?
i was thinking for 37's i would go 5.38's for my 10-bolt front and 10-bolt rear

i read somewhere that because i have a 350 and 700R4, i would have a 27 or 28 spline?

 

[swettysblazer]

Your rear axle should be a 30 spline if it is stock. Best way to be 100 percent certain is to pull an axle shaft and count the splines but that takes time.

27 spline is referring to the t-case, so nothing to really worry about there.

5.38's is pretty deep for 37's, especially on a rear 10 bolt. I would be worried about the pinion being super small on that and possibly being weakened. What are your plans for the truck?

 

[Chickntrk]

Your rear axle should be a 30 spline if it is stock. Best way to be 100 percent certain is to pull an axle shaft and count the splines but that takes time.

27 spline is referring to the t-case, so nothing to really worry about there.

5.38's is pretty deep for 37's, especially on a rear 10 bolt. I would be worried about the pinion being super small on that and possibly being weakened. What are your plans for the truck?

I agree....that pinion is gonna be tiny! Id be nervous about 37s on a rear 10 bolt in general. I wouldn't put any sort of locker in the front 10 bolt if you want it to live with 37s. I wouldn't think you'd need anything lower than 5.13s for 37s.

 

[jteck10]

Your rear axle should be a 30 spline if it is stock. Best way to be 100 percent certain is to pull an axle shaft and count the splines but that takes time.

27 spline is referring to the t-case, so nothing to really worry about there.

5.38's is pretty deep for 37's, especially on a rear 10 bolt. I would be worried about the pinion being super small on that and possibly being weakened. What are your plans for the truck?

I agree....that pinion is gonna be tiny! Id be nervous about 37s on a rear 10 bolt in general. I wouldn't put any sort of locker in the front 10 bolt if you want it to live with 37s. I wouldn't think you'd need anything lower than 5.13s for 37s.

got it. yea i called a shop and he suggested 4.88 or 5.13's
mainly going to be a pavement princess with occasional sand-dunes and mild dirt roads
i do have manual lockers up front as well

sounds like 5.13's is the ticket until i upgrade axles?

 

[Chickntrk]

Manual locking hubs? I meant like a differential locker….personally I wouldn’t put money into a rear 10 bolt, get a 14bff and regear that along with your front 10 bolt

 

[nvrenuf]

I'm all about deep gears but I have to agree that the rear 10 bolt may not be the best. For the money you may spend, I would search for a 6 lug 14 bolt semi floater and regear it. The 14 bolt semi floater isn't as beefy as a full floater but it's a lot better than the 10 bolt.

 

[cheavyk10]

Also depending on the year of your rig the 10 bolt could have 28 spline or 30 spline axle shafts. 30 spline 10 bolts appeared around 1988.
I grenaded my 28 spline rear 10 bolt with 4.10s and an open diff doing clutch dumps on pavement with 35" tires. I broke the spider gears and sent them through the ring and pinion.

 

[Chickntrk]

I'm all about deep gears but I have to agree that the rear 10 bolt may not be the best. For the money you may spend, I would search for a 6 lug 14 bolt semi floater and regear it. The 14 bolt semi floater isn't as beefy as a full floater but it's a lot better than the 10 bolt.

And it’s 6 lug to match your front!

 

[jteck10]

this helps a ton, thanks all! sounds like i should leave at 35s and current gears until i find new axles, then spend the money where it matters

 

[obijuank5]

Honestly, the 10 bolt will be plenty fine for your use imo. I use to do burnouts on my auburn with stock 30 splines and 37s. Weekend wheeler and daily driver/commuter. I did front wheel bearings more than I ever worked on the rear diff.

I'm the first to say go I overboard on literally everything I do but, also but have no problem suggesting 37s and 4.88s. Been there done that and crushed the car with em.