What to do with my big truck build?

So I have a long term back burner project truck. A 1970 C50.

It's insanely fun to drive. Kind of. My buddy nicknamed it the Zipper because it's like a crappy carnival ride. You're not exactly sure if you're going to make it out alive. Well the plan for this truck was to drop a newer small block (probably a spare LS) in it while retaining the manual trans. Then add some newer axles, airbags and a hooklift for a flatbed. I had the front brakes relined a few years ago and the guy said parts were basically unobtainium which is what prompted the axle swap. Unfortunately, I've come upon a problem. As said, currently it's a manual trans(SM465) with a drum parking brake mounted to it. I couldn't find a newer overdrive manual trans with a drum attached but I found that the newer chevy 4500 trucks come with a parking brake mounted on the diff pinion. Perfect! Ordered a front beam and a rear diff!

The clever among you will see that diff does not have a parking brake drum mounted to it. They thought it was a '17 and it's actually something closer to an '07. Great. Well they don't have the correct one and wouldn't take it back. eBay sided with me and gave a full refund. I tried to work with the wrecking yard about splitting costs to ship it back or them relisting it and shipping it straight from my place but they ghosted me now I have a free rear diff that I'm not sure I can use...

What direction do I go now? There doesn't appear any easy way to add a parking drum to this diff short of replacing the whole third member with a newer version. Which I'm not opposed to doing but I just don't know if it'll work. Do I go back to a parking drum on the trans with some funky bracketry? Do I ditch this diff entirely and keep searching for one with a drum on it? What says the hive?

What about just using line locks?

Is there a normal parking brake on that rear end? If so, it shouldn't be too hard to just use that. 

If there isn't already already a parking brake provision on that diff, I would be looking into using/adapting a disc parking brake on either the differential, trans output, or a pair of parking brake calipers on the existing rear discs.

That diff evidently came from an ambulance that had an allison trans with parking brake mounted to it. The calipers don't have any provisions for an e brake. 

gsettle said:

What about just using line locks?

Something about holding line pressure for extended periods of time makes me nervous. Is that tested long term solution or is it something that a few people have done a handful of times?

In reply to iansane :

The MICO brand locks are known in the heavy truck industry. 

They have an Electrically operated one, but also several manually operated ones.  They're the standard. 

I have a generic line lock on my Toyota off road truck but it get's hot and I don't trust it for long periods of time - only long enough to stop and run back in the shop or long enough to chock the truck.

iansane said:

That diff evidently came from an ambulance that had an allison trans with parking brake mounted to it. The calipers don't have any provisions for an e brake. 

That's why I said to adapt calipers with parking brake provisions to the existing rear discs or a driveshaft disc parking brake to it.   This is done all the time in the street rod and 4x4 world.

There is plenty of room to hang a second set of cable operated calipers on the discs, as well.

Russian Warship, Go Berkeley Yourself said:

iansane said:

That diff evidently came from an ambulance that had an allison trans with parking brake mounted to it. The calipers don't have any provisions for an e brake. 

That's why I said to adapt calipers with parking brake provisions to the existing rear discs or a driveshaft disc parking brake to it.   This is done all the time in the street rod and 4x4 world.

 

There is plenty of room to hang a second set of cable operated calipers on the discs, as well.

I've seen that setup before, like on portal axles. The difference between the 4x4/street rod world and this is this has nowhere to bolt the caliper to short of drilling and tapping the center section. I could go off the center section-to-diff housing bolts but that's a huge bracket. This diff is big. A separate parking brake caliper on the stock discs is a possibility but I just question their holding capacity for a ton and half truck or if they'd even straddle an 1.5" thick rotor

Doing some more research it looks like it's a Dana diff. S135. Technically an S135SL but the S135 and S150 supposedly have the same center section (obviously sans brake mounting). I think I can just get a used center section with the brake assembly already on it and just pop it in. Maybe.

Brief googling indicates that an NV4500 with a parking brake is a thing.  Gets you OD and keeps the brake.

Our boys at Wilwood make mechanical calipers at $100ish a corner.

Seems to be one of the easier and sensible-er solutions to just add parking brake calipers to the existing rear rotors on your new rear axle.  Plenty of room to weld on a new caliper mount as well on that big axle.

93gsxturbo said:

Our boys at Wilwood make mechanical calipers at $100ish a corner.

Seems to be one of the easier and sensible-er solutions to just add parking brake calipers to the existing rear rotors on your new rear axle.  Plenty of room to weld on a new caliper mount as well on that big axle.

I don't see anything in their arsenal that will fit over a 1.4" thick rotor. Am I missing one?

In reply to Uncle David (Forum Supporter) :

If swapping the center section doesn't work I think this would be the easiest option. I was hoping to use the newer tr4050 trans but the nv4500 was definitely on the radar. And I could use all factory stuff to bolt it to an LS engine...

HotNotch said:

In reply to iansane :

The MICO brand locks are known in the heavy truck industry. 

They have an Electrically operated one, but also several manually operated ones.  They're the standard. 

I have a generic line lock on my Toyota off road truck but it get's hot and I don't trust it for long periods of time - only long enough to stop and run back in the shop or long enough to chock the truck.

That looks pretty easy as well. I'll have to poke around on their page. I think part of the reason I was shying away from the line lock application was because of the visceral nature of throwing the parking brake lever. It's just cool! Haha.

I had a 95 International with a Spicer 5 speed OD trans and trans mounted parking brake. There's probably an SAE bellhousing to adapt it to a GM engine. 

Brings back memories.  Not all of them good.  I spent a good part of my youth in a '69 C-60.  366.  4 barrel Holley.  About 6 mpg loaded.  A contemporary Ford will usually not run as well nor look as good but is otherwise a superior truck.  At least that's my experience and I have more than 1 data point.  LOL.  Actually I liked IH better than any of them.  392 Binder might be the most underrated domestic V8 there was.  Those things can run.  Check out Finnegan's Garage.  He did a C50 like yours with a blown 454 if I remember correctly.

In reply to A 401 CJ :

It could be worse. My first flatbed was a former NYC truck. A C50 with a steel rollback and a straight six. With two cars there was no guarantee you could get up to forth gear 

Hey, wait.  Doesn't that have a 2-speed rear?  Why would you want to give up that?

Can you flip a second pair of thin discs and mount them like inboard spacers, then hang a caliper off a short bracket and use those as your parking brakes?

That thing must have a multi piece driveshaft, what about putting the parking brake at a joint in the driveline? 
 

similar to this, but independent of the trans or diff. At a center support/carrier bearing.

Running into a similar situation with a transmission swap on a motorhome. I have this same axle and the Allison transmission I plan to install does not have the parking brake drum on the tail shaft. Did You find any kits to add the drum to that axle. I also was thinking about adding a disc setup on one of the driveline center supports but of course looking to see of there is a easy option to just bolt parts on.

The mudding world regularly bolts calipers and rotors to differentials.  Might be a source?

In reply to bkhitech :

This became ultra back burner project when I bought a basically completed c30 ramptruck. I don't know why but putting the parking brake in the middle of the drive line gives me the heebie jeebies. Which doesn't really make sense because it's really no different than putting it at one end. Nevertheless, I didn't pursue it. I have two possible solutions in my mind. I kind of like the 7.3 in my f350 in a kind of masochistic way. So, either swap a powerstroke in with a factory trans mounted parking brake or build a caliper/drum mount around the center section of this diff to mimic a factory setup. Or I guess thirdly I could swap the center section with one that has provision for a parking brake. All the part numbers look make it look possible. The hodgepodge caliper mount to this diff would have to be ridiculously beefy because the only place to bolt it on would be the centersection to housing bolts and that's a lot of torque.

But, like the 6 cars in front of this on my list of projects, I haven't gotten a lot done on it.