Gday everyone.
I have a couple of questions regarding my ’76 F100.
It seems it was built as an ambulance and has had a cab swap, though as the compliance plate and option plate are both missing, I am not 100% sure.
It has 3” rear springs and a ¾ ton load rating (according to the registration papers) and the ambulance was the only ’76 F100 so equipped.
The rear springs have 6 leaves, with an extra at the top which doesn’t seem to do anything. The hangers and shackles all appear to be original, as they are riveted, rather than bolted as they would be if they had been replaced.

First question.
If I want to order hangers and shackles to lower the rear, what will I have to order them for, as obviously the parts for a ’76 F100 with a 2 ½” rear spring are not going to work?

Second question.
I also want to soften the rear suspension. The plan was to reduce the amount of leaves in the rear springs.
Which leaves would you take out?

The F100 is going to be used as a parts chaser, with a bit of towing to a maximum of 4500 lbs.

 

That separate top leaf spring is just an overload spring, I am sure there USE to be some bump stop brackets on the side of the frame, taking it off will not hurt thing. Hang in there, some 2wd guys will chime in with the how to lower it advice.

 

Agree the overload spring can go. For the rest, suggest you find and consult with a local spring shop. They can probably advise how to modify the spring pack for your use. Since you are towing, probably should not go too low or too soft... a 4,500# trailer will want about 450# tongue weight on the hitch. You do not want too much sag when towing.

Another approach is to take out several spring leaves to soften it quite a bit and add air bags. When loaded or towing, air up the bags to limit the sag.

 

Lemme answer your questions in reverse because what you're asking for relates to both static height when loaded or unloaded...

If ya wanna soften the ride, remove the overload spring at the bottom. But since you wanna tow, keep the helper spring and set them up to actuate or begin "working" when a trailer is hooked up... sounds like you need the frame-stop brackets if you don't have 'em. Easy enough to fabricate... OR make them adjustable.

Leveling? I'd look into flipping the front hanger of the rear leaf springs... a half-flip as pictured below. It'll drop ya about 2.5... BUT... you can do some "adjustment" by keeping the helper spring.



FYI....This is a full flip:

 

Ok, I found the compliance plate and option plate on my truck.
It wasn't built as an ambulance, but was optioned with the ambulance H/duty rear suspension including the rear stabilizer bar and a special fleet paint colour.


Anyway, I am going to try to level it and soften it by reducing the number of leaves to 3, and use overload spring for towing as suggested by HIO Silver.