Silly me...... first thing to check is your air pressures.

with 37” tires the correct pressures at max GVWR of the Ex is 35 psi.

(I run 40 due to preference because my BFG tires have a fairly soft sidewall.)

you can see the load and inflation tables here
https://toyo-arhxo0vh6d1oh9i0c.stack...s_20170203.pdfp

Pirate, The rear block absolutely needs to go, no matter what he does with his X. The X definitely needs a rear sway bar, they all do. Lifted or not! Mine is stock and it was installed at 17k miles. Nothing wore out, it just wandered due to the soft springs, and if the tires are rated at 80psi they should be close to that pressure. If they are only rated at 40-50 psi then they should be set at 50. Everything else you mention is correct.

OP, the snubbers we are talking about go on the front of the half leaf. The one hanging out there by itself with the missing rubber block, you can see some of it left, it is bolted to the spring. However when you get the right springs that will be gone. The add a leaf is one of the leaves in the rear spring pack that doesn’t look factory. The factory leaves have plastic silencers in them, you can see where there are holes with the plastic pad snapped into it. The add aleaf is bolted into the spring pack, you can see it in the 3rd rear suspension picture. Bottom line get rid of those rear springs and lift blocks.

Ahhh an engineer! That explains a lot! All knowledge is based on paper, but when it comes to actual real world use it gets lost. Show me one off road rig with lift blocks that actually works. Yes I know how air pressures work. I also know what does and doesn’t work firsthand. And I along with everyone else knows how terrible the factory rear springs are in the X, no debate there! not even going to argue any longer!

OP, just do what the majority of us are recommending. We all tow and know what the X can and can’t do.

Good lick!

IMO your alignment specs are your first order of business to sort out and likely the single largest contributer to the poor handeling of your excursion.

if the shop you took it to told you it is fine you need to find another shop who is familiar with straight axle vehicles.
your toe is not in in spec and while your caster is in spec it is horrible. Keep in mind that even with all settings in spec you can stil create an ill handeling vehicle due to the possible combinations, the goal is to get within spec and a satisfactory combination of settings.

like I stated earlier the Ex handles best at a full 5.5 degrees of caster.
The spec is 3.5 +\- 2* and your at 2.1 and 2.2 is going to produce a squirrelly girl, especially with 0 toe.

find a shop that will put the caster to 5.5* and then put in a little toe in. ( Think mine is currently at +.5*)

any alinment shop worth their salt salt will also inspect all front steering and suspension components for wear as a proper alignment can not be done with loose bits.

i will answer your other questions in a separate post.

nope, I’m not an engineer I am a racer, I was hired because my real world experience and setups worked better then their companies engineers setups. Proven by winning the Baja 1000 4 times.

Nothing terrible with the factory rear springs, they just work better with more travel but that doesn’t make them terrible.
the “terrible” thing about the factory springs is the front springs sag and that exerbates the factor alignment setup they put in these.

When people do the modded rear spring setup they are really taking the Excursion 5” travel spring with 420lbs inch spring rate off and putting on softer F250 springs, But because the f250 main springs are to soft for the Ex you mods them using the Ex bottom 2 leafs, the modded spring now has the same 420 lb in. Spring rate as the stock spring but with 8” of travel.

So if the stock Excursion springs are to soft I am asking why everybody doing the B mod setup make them the same spring rate as stock ? Answer, Because the stock springs are not “to soft” . Even if they were wander would not be the handeling trait produced, a lower ride height and lower payload capacity would be the result.

An off road race vehicle would not likely use a lift block as they would be after maximum suspension travel at the lowest possible ride height.

For street use including towing look no further then the F250 trucks. It works fine as long as you have axle wrap under control and your setup has enough travel to accomplish its tasks.

the Op made zero mention of anything remotely related to axle wrap issues even though his anti-wrap bar which controls axle wrap is missing a key component. So like I said, the tall lift block would best to be replaced with a spring with more travel but I see no indication his current setup is running out of travel and bottoming out so no need to remove the block to fix the wander problem he is trying to solve.

the add a leaf leaf that I see on your is the second leaf from the bottom.

I circled the snubber, it is attached to the anti-wrap bar. ( this is not the first leaf spring )

the axle weights you listed are the trailers capacity, how you actually have it loaded and setup will determine how it handles and what changes may need to be made, I.e. a WD hitch and what size bar will be needed.

Fwiw, my 9000 boat trailer does not require WD hitch, my 7000 lb car trailer does not require a WD hitch
My 10,000 camper trailer needs a WD hitch, my 14,000 toy hauler needs a WD hitch.

so you see no issue running those tall blocks (I’m guesstimating at 4”, plus the factory X block! Come on now? Maybe you think he is pretty good at what he does, but recommending it is OK to
run those blocks with 37” tires and towing a trailer is Ok is a gamble! I for one do not take any worth out of anything he posts just from those statements alone. And yes the F250’s run blocks and don’t have wandering issues because the springs aren’t weak (read compliant) like the X! OK, now I’m done posting here. I’m really hoping the OP can see through all of this, who is doing it right and who is recommending things based on beliefs.

good luck to the OP. If you want you can PM me or even Tom aka WE3ZS