The Stovebolt Site Forums The Shop Area The HiPo Shop Mustang 2 Suspension Packages vs. 1/2 ton swap out

I have a 51 GMC 3/4 ton, I am considering two options; change out the front axle to a 1/2 front and install disc brakes, or install a Mustang 2 suspension. My question what is involved to install the M2 suspension. Do I have to pull the engine out, or just slip out the old straight axle and bolt in the M2 suspension. Can anyone enlighten me on this issue on what is all involve here besides the expensive cost of the M3 suspension? Also is there a shop in the So Cal are that does this type of work reasonably?

The Mustang II kits are all designed for 1/2-ton trucks, so will require modification to work on your 3/4-ton. Most the kits I've seen require boxing the frame in the area where the suspension attaches, and that would be much easier to do with the motor out of the way.

thanks for the info, I didn't know those kits were for 1/2 tons only.

I thought The front on chevy 1/2 ton and 3/4 ton -51- are the same. Not GMC ?
Pat

I believe that both are the same up front. The rear spring setup is the the main difference. 3/4 ton springs sit on the outside of the frame rails while the 1/2 tons mounted under the frame. I've seen several guys with 3/4 tons use the MII. Check with Big Chevy 3600. He's running the Mustang II on his 3600.
I used the ifs from a '79 1/2 ton myself but there are other choices available. Scott Danforth listed them earlier in this forum.

My goal is to get this GMC up and running after 16 years setting in my garage for the next Good Guys Car Show at Del Mar Race Track in Del Mar Calif., Then cruse up the coast on PCH 101.

My kit will fit a 3/4T. And it is NOT a Mustang variant.

Check out my pics. It's a 51 3/4 ton and equipped with a Heidts IFS. 1/2 tons are the same as 3/4 tons up front once you remove the suspension.
http://www.heidts.com/heidts_superide_ii_truck_complete_package.html

Well Junky, wat did you decide on?

I thought the frame material was thicker, which I'd expect to cause problems with boxing plates. Am I mistaken?

According to THIS page there seems to be a difference. The width might be the same(doesn't show info), BUT the thickness of the frame is different...Joe

The height is different by .093" and the frame thickness is 10 gauge on the 1/2 ton and 7 gauge on the 3/4 ton.

My cross member kit still fits fine, however there is now a small gap that needs an extra 1/2 hour of welding. I also have 7 gauge boxing plates for those that want same thickness on the boxing plates.

So Scott any idea what the Mustang II vendors are doing to deal with the descrepancy?

I'm not surprised you have a solution, but don't like hearing everyone say the Mustang option fits both when there seems to be some modification required.

Of course I've not done anyone's kit...

The whole adventure is a task in modification 1/2 ton or 3/4 ton. It's certainly not a Tinker Toy undertaking. And no the vendors don't seem to want to build much of anything for the 3/4 tons. It has been my experience that most things designed for the 1/2 ton will fit the 3/4 ton with minor tweaking.
That's what makes it fun.

I bought a complete 1/2 front axle, it was in good condition and only $150.00 such a deal. I ordered new hardware for it, I want to replace the old fatigued bolts, just want to be keep things together being safe going down the road. I want to get this truck running down the road, but I don't have a lot of cash now, so for now the straight axle I bought will work just fine, I need to swap out the old 3/4 ton rear axle, any ideas what I can swap it out for? I want to go with a 5 lug patten, and get rims and tires for my Junky 51 GMC.

I used the rear axle from a '73 Chevelle under mine. Do a little searching here, lots of possible choices have been used.

Would a rear end from an old S10 work?

Jimmy... this article might help.

I used an 80' Camaro w/posi and then bought a set of disc brakes off a 2002 Trans Am which will bolt on.

I would suspect that they either have a bit of slop in their design, or their instructions read torch to shape, grind to fit, paint to match.

Since the bottom and outside of the frame are nearly the same, they most likely will be locating it on the bottom and outside

Best bet, if you are have questions call the vendor.