What can I do to beef up the suspension of a 78 F250 supercab?
 

I'm wondering what I can do to beef up the suspension for towing and just to be overall stronger. I'm assuming shocks, leaf springs etc. but I'm not sure how to choose the right shocks or any of that.

Since it's a 250 supercab it has leaf springs in the front and I'm pretty sure there is an add a leaf kit already on it, there's 9 leafs in the rear and 3 in the front, I'm not sure what stock is. I'm also going to swap out the 3.53 gears with 3.73's into the dana 60 rear and I'm assuming it's a dana 44 front, I can't find any number plates because it's all covered in sludge right now. I would go with 4.10's but I'm keeping my 33" wheels for now and want to get better than 5 gallons to the mile but still pull on occasion, I don't do a whole lot of hauling besides during hay season and to move cars so I figure 3.73's are a happy medium between the 3.53's in there now and the 4.10's that would help tow.

So what else should I look for? Would it benefit to get new shocks and if so how do I figure what I need? Would it benefit to just get new leaf springs at the same time so they are new and not worn out?

You might check to see if F-350 springs will fit , i don't know if they will or not. I'm guessing they will be more heavy duty. Other than that just add more to your spring packs i guess.

Well there aren't any coil springs on it that I've seen. It's all leaf springs and shocks. Here's some pictures of it. They aren't direct pictures of the suspension but you can see it in them.

http://i1179.photobucket.com/albums/...ps6b17aafa.jpg
http://i1179.photobucket.com/albums/...pse20ed753.jpg

Oh yeah 4x4 , that last picture looks like the right front ? The spring pack looks like it curves over the mount a little bit . I wonder if it has a broken leaf or is just weak. New spring pack with one more leaves may do it , those look a little crooked too . I would have thought a 4x4 would have a bigger spring pack , more leaves . Never owned one so i could be wrong , had a bronco once but it had front coils.

Front pack was two leafs stock, so you have an added leaf. Even with the addded leaf your front will look flat. Mine is that way and the extra leaf gave me almost two inches lift.

I only have a five pack on the back, which I believe is stock, so you already have extra leafs added on the back as well.

1973 - 1979 F350 leaf springs

I'd start here.

Beefing the leaf springs means adding overload springs or adding leafs - straight forward as you posted. There is a downside. If it is stiffened for really heavy loads it may ride very poorly when empty. My '78 sure did with heavy overloads installed.

My overloads and main springs were in bad shape so I replaced with standard F250 springs and new gas shocks (Gabriel from memory, just good parts store shocks). The improvement in ride was amazing. When I do occasionally load it heavy (eg 2500-3000#) it sags some but handles OK.

If I loaded heavy a lot, I'd add air bags. Let the air out for a decent ride or air them up for the heavy load.

I've looked at the air bags before but haven't been sure if I wanted to jump at them, I just looked up the load lifter 5000 that LMC sells and one company says it requires some 5th wheel hitch and others don't. I'm wondering if they would rub the wheels though since I have 12.5" wheels and it looks like air bags install between the leaf springs and wheel but LMC shows them on top of the leafs.

I bought my bags at summit. They were simple to install. The upper part mounts to the frame and bottom to the leaf spring 12.5 wide tires are no problem.

Personally I would start with new springs all around and keep the ad-a-leafs. You can also slip an overload under the ad-a-leaf.
Adding a sway bar can go a long way towards steadying the ride too without any noticeable effect on springs.
Shocks are subjective. I always select them for running empty which my truck is 99.99% percent of the time.
As for gearing, have you considered the gear venders over/under or under drives?
Spendy for sure but I know of a few pickups running them and the owners swear by them.
Gear Vendors under/overdrive transmissions the most awarded auxiliary transmissions.

Swapped SD leaf springs
 

I have a buddy that swapped in some super duty leaf springs in his 79 F250 SC 4x4 and he said you wouldn't believe how is handles now...I don't know all the details to his swap, but you might do a search on here for something like that, I'm sure its been done here. If you are interested I can find out more from my buddy if you want?

here you go:

99-04 super duty leaf spring lift in 71 f250 - Ford Truck Enthusiasts Forums