it is possible.... the wheelwells on most vehicles are actually cut larger in the front, as those tires move... the rears only go up and down, not side to side

 

the front wells are a little bigger but you can see the back end is lower than the front and there is no visible reason in the back as far as suspension sag.
i wonder if the front springs are not larger than the originals if they were changed, it has 281K so they may have beeen,

 

I gotta see a pic...

the only things I have seen that makes the rear lower than the front are:

broken spring
broken spring mount
worn springs
broken/worn body mounts
different tires sizes
air shocks that are totally deflated
air bags that are totally deflated

what you should do first is take measurements from the ground to the bottom of the fender/quarter panel then compare it to another van of your type to see what side you are really dealing with.

I am not sure which way your shackles should go on your van. I would hope someone can chime in and say which way they should go. I think you are right, but I was you I would pay the $2 entry fee to the junk yard and look at other vans to see if your stuff is on right...

As for shocks not being for the 4000 lbs axel, that has to do with just the naming...it is just another way of saying dont use on the heavy duty suspension. The reason it probably says that is the shock would wear prematurely...that's all.

You can find other shocks...you can also match up shocks sometimes at a parts house. So, there are options. From what I can see, the F350 shocks from the 90s on may work...

 

hard to measure a van to compare to mine unless i climb under it to see if it has the same front end.
my van came with 2 different ones.
the junkyard i go to does not have any B3500, they have some B1500 and a B2500, i go there to check on what they have for vans on the weekend.

the shocks for the rear say excluding 4000# front axle which would make sense if that setup uses a heavy duty rear suspension.
why didn't they just say excludes heavy duty suspension?
i am going with shocks that are specific for my van, i don't want to take the chance of ruining the new shocks because they are not built to handle the suspension.

i don't mind the back being lower, it does not drag on the ground at any time and i can still climb under it without a jack.
it is built into a camper and the height stayed the same, i haven't filled the fresh water tank yet and i don't have the grey water tank to test it, it is 40 gallons of water if they are both full and both tanks are on the same side.
the other side has the battery box for 4 64 pound batteries that are not in yet.
it is a 1 ton van so it should handle the weight.

 

you said it has new rear springs, does it have new 1 ton rear springs? I wonder if the new rear springs are 1/2 springs or 3/4 ton springs and hte reason why it is sagging?

 

they are 1 ton springs.
as i mentioned it is not sagging.
the back is lower but the springs are not sagging.

 

I would use Bilstein shocks on a conversion van, I intend to put a set on my van come spring. If you go on Rock Auto and check front end parts you'll see that many parts interchange between the early B150s and the late B3500s. The difference being the springs, shocks, and hubs.
I suggest you take your van over a scale to check your weight on each axle. You do not want it lifting the front axle going over a speed bumps. It may not even be safe for you to drive on the highway with the problem you are describing.
Cheers, Steve

 

what do you mean by lift the front axle?
i have had it on the highway a lot and up to 75 with no issues.
if you look at the van from the side you can see the back is a little lower but not drastically lower.
the height with everything i have in it never changed, i don't think i am near max.
they use these extended B3500 vans for making high top 21 foot class B RVs and the only change to the suspension is a heavier duty shock like the Bilstein, they have the same springs and the 4000# front axles.
i would love to find one in the junkyard, i would be there all day pulling parts.

 

You want to make sure you have proper weight distribution. I have weighed a few Roadtrek conversion vans and they keep the front axle close to the legal limit. Too little weight up front is dangerous, your front wheels will be wobbly and in extreme cases it will lift the front wheels off the ground. I've seen that with short 1-ton trucks that have heavy loads in the back of service beds.
My assumption is that you have a balance problem if the front of your van is unusually high. I have not checked your video but perhaps you could post a couple photos to look at.
Steve

 

i attached a pic i took this morning.
it doesn't look like it is extreme for the difference in height.