68 GMC Stepside Axle

[pcunningham]

Hi everyone. I'm new here so bare with me if this topic has already been discussed. I have a 68 GMC Stepside that came with the 250 I-6 with the 3 on the tree. In the near future I am going to swap out that engine and trans for a SBC or BB but I'm not sure if the stock rear axle can handle the torque. So, my question is: What newer production vehicle with rear disc brakes will allow me to take it's axle and put it in my GMC? Thanks in advance.

[michael bustamante]

Do you have leaf suspension like most gmc's or coil springs? Are you wanting five lug or 6 lug?

[pcunningham]

I have leaf springs and I'd like to go with 5 lugs.

[Fitz]

Originally Posted by pcunningham

Hi everyone. I'm new here so bare with me if this topic has already been discussed. I have a 68 GMC Stepside that came with the 250 I-6 with the 3 on the tree. In the near future I am going to swap out that engine and trans for a SBC or BB but I'm not sure if the stock rear axle can handle the torque. So, my question is: What newer production vehicle with rear disc brakes will allow me to take it's axle and put it in my GMC? Thanks in advance.

That diff should be a 12 bolt. It is more than capable of standing up to a big block.

[special-K]

Unless you are going for some crazy power the 12-bolt will be fine. They've run these trucks all these years with everything from a 250 to 454s and 6.2 diesels. You'll be fine. gMC did put Dana 60s in some 1/2 tons,but those were back in the 6-lug days. A Lincoln 9" rear with disc brakes is a hot swap. Those have 5 on 5 pattern. I want to say two more things. One is welcome to the board! the other is, now that you have a GMC and you're on the most informed GM truck site on the internet, you need to get sed to calling your truck a Fenderside. That's what GMC called them. Chevys are Stepsides.

[gipper]

I never knew that Special-K

[68GMCCustom]

my '68 GMC w/305 V6 and 3OTT had a Dana44 when I got it. Not sure....but thought it to be original.

[mechanicalman]

Originally Posted by special-K

Unless you are going for some crazy power the 12-bolt will be fine. They've run these trucks all these years with everything from a 250 to 454s and 6.2 diesels. You'll be fine. gMC did put Dana 60s in some 1/2 tons,but those were back in the 6-lug days. A Lincoln 9" rear with disc brakes is a hot swap. Those have 5 on 5 pattern. I want to say two more things. One is welcome to the board! the other is, now that you have a GMC and you're on the most informed GM truck site on the internet, you need to get sed to calling your truck a Fenderside. That's what GMC called them. Chevys are Stepsides.

Wow I think I had heard about the "fender-sides" before but had completely forgotten about that.

I have seen GMC's with 6 lug diffs that had 10 bolts on the cover. I wonder if that could have been a Dana?

[pcunningham]

Special-K, thanks for the info - I didn't know that either about the fenderside. I'm going to take a closer look tomorrow to see what axle I have but from some of the pics and info I found today that it might be a Dana 44.

[Ozzy2013]

Originally Posted by special-K

Unless you are going for some crazy power the 12-bolt will be fine. They've run these trucks all these years with everything from a 250 to 454s and 6.2 diesels. You'll be fine. gMC did put Dana 60s in some 1/2 tons,but those were back in the 6-lug days. A Lincoln 9" rear with disc brakes is a hot swap. Those have 5 on 5 pattern. I want to say two more things. One is welcome to the board! the other is, now that you have a GMC and you're on the most informed GM truck site on the internet, you need to get sed to calling your truck a Fenderside. That's what GMC called them. Chevys are Stepsides.

What year Lincoln 9 inch rear fits?I have a dana44 in my 68 GMC stepside and its all stock.CAre these dana 44 any good for 500hp?

[Bob B.]

Dana 44's are not uncommon in GMC 1500's in '67 and '68. A semi-floating 6 stud Dana 60 was an option, but is fairly rare. Full floating 8 stud 60's are very common in GMC 2500's. Remember that for the most part, GMC used Dana-Spicer and Chevy used Eaton/Corporate axles in '67 and '68, but there are exceptions.

[special-K]

Yeah, I forgot to mention Dana 44s, but the Dana 60 would be the brute bolt-in...if you found one. I have built trucks (pro-street) using custom built Mark Williams Dana 60 5-lug. Ain't cheap! I forget what year Lincolns had that rear, but I know of people using them in the early-90s, so back around then and into the '80s. Probably the first years they put disc brakes on.

[Ozzy2013]

Thanks for the info i dont know what i will go with yet wish there was more info on the dana 44 .

[Bob B.]

The Dana 44 is a very common rear axle, just not in GM trucks! Check some of the Jeep and other off-road forums.

[Ozzy2013]

Ive looked all over and cant find info about strength of the unit and how they hold up.

[mechanicalman]

Originally Posted by Ozzy2013

Ive looked all over and cant find info about strength of the unit and how they hold up.

I worked at a Pontiac/Jeep dealership for about 6 months in the late 80s. Being low man on the totem pole, and willing to do diffs, I got stuck with a whole bunch of Dana 44s.

Never saw one die, but they whined in pain a lot (my pain!) LOL.

Gear whine, seems like way too many of them. New gears didn't fix them, they had to have the backlash re-set mostly and a few needed the pinion depth re-set. Re-setting the backlash was difficult, the shims are behind the bearings where they are pressed onto the carrier, unlike "normal" diffs where the shims are behind the bearing cups. The dealership was small time so they didn't have the tools that were shown in the shop manual for pulling the bearings so I had to cut the bearings and replace them every time I made a ring gear endplay adjustment.

So, they help up good from what I saw in my limited experience, and I've always heard they are good. I'm just one who hates to work on them LOL

Back in 67-68 I believe people were a lot more tolerant of a little gear whine so it would be interesting to me if the old ones whined and if it was considered normal.

[Ozzy2013]

Wow thats messed up!lol Im thinking ill go with a dana 60 or a 9 inch ford

[special-K]

The Dana 44 was used in the front of virtually all American 1/2-3/4t 4wd trucks as well as Jeeps, Broncos, and Scouts (& in rears) for many many years. GM started using 10-bolts by around 1980 and the general opinion is they are about equal in strength. Some parts are even interchangeable. 10-bolt to 12-bolt has it's differences, yet they seem to perform fairly equally. I'd say run whatever you have and if it doesn't hold up start looking into a beefier rear, or beef up the 12-bolt. 12-bolts and Dana 44s took the power from a BBC and put it to the road for many decades.

[Tinkermc]

Welcome to the Best GMC Forum.

[mechanicalman]

Originally Posted by Ozzy2013

Wow thats messed up!lol Im thinking ill go with a dana 60 or a 9 inch ford

Well, IMO, it depends on what you want to do with it. 9 inch Ford a very good choice, but if you are under 375lbs TQ and your Dana does not whine, I see no reason to change it.

Also, a differential comes apart much quicker when abused with a manual shifted trans than an automatic trans because a torque converter is much more forgiving than a clutch.

Didn't mean to scare you, I just don't like working on them.

[Ozzy2013]

Im going to build a ford 9 inch the 44 in my truck is a open rear and my 402 is making over 550 ftlbs at the wheel.Thanks for all the info .

[special-K]

www.markwilliams.com

9" rears are good rears, that's what that Lincoln rear is. I wouldn't tell you what to do, but I would like to give you a place to look at all your options. I just like the idea of running a rear that cold at least be found in another GM, if not my model. The Dana 60 in a car or 1/2t pickup is a badass unit! Figure the hottest Mopars used the Dana60, a special few of these 1500s, all 2500s, some C/20, Ford F250s and Dodge D/W200s.

[pcunningham]

I took a good look at it this weekend and the axle has 44-I stamped on the bottom right side so I do believe I have a Dana 44. So, I have a Dana 44 rear with 6 lugs and leaf springs. Does anyone know if they will hold up to around 475 lbs torque?

I just bought this new toy 3 weeks ago and it is making me a very happy camper right now but the changes I have planned will be awesome. What do ya'll think of her?

[Devins-step]

Originally Posted by pcunningham

I took a good look at it this weekend and the axle has 44-I stamped on the bottom right side so I do believe I have a Dana 44. So, I have a Dana 44 rear with 6 lugs and leaf springs. Does anyone know if they will hold up to around 475 lbs torque?

I just bought this new toy 3 weeks ago and it is making me a very happy camper right now but the changes I have planned will be awesome. What do ya'll think of her?

Awesome looking truck. I am near Brandon. I hope to have my '72 stepper back in time for this month's car show in Plant City. You hit any of the cruise ins in the area? I see a Camaro in the pic too. Here are my two money pits.

[Devins-step]

Forgot to upload the pics...
Dan