I think video explains everything:
https://streamable.com/9ayv1t
Sideboard Bed + Crane + Steel Beams gives similar results:
https://streamable.com/0p6ral
Even with stock bumper it's having issues, needs stiffer suspension in the front or something.
It's done this since day 1. I never use anything other than stock but even that still can impact as you say.
"This truck is NOT sponsored by Oehlins Suspensions" 
The most bouncy thing I know - Zikz and take the "tree road" at Quarry near your service station. Needs nearly a "flight stick" to be still controlled ....
Funny, I noticed this yesterday when I placed a fuel tank on it. It becomes the low rider of trucks for sure, when a heavy load is placed on it. However, it is extremely powerful. I usually sell this one anyway.
From 8.0 patchnotes:
- Fixed incorrect collision and behavior of International Transtar 4070A with Trapezium bumper and Fuel Tank attached (or other heavy load)
Ok so I did some testing and it seems that all they did is - raise the suspension
(red is 8.0)
This helped a ton with clearance issues. Stock bumper + fuel tank has no issues now, but trapezium + fuel tank still is questionable:
https://streamable.com/g6dn87
Maybe you guys could trim the collision model on trapezium bumper a little bit? Like you did with the belly of Kolob. That would solve this issue for good.
Still a huge improvement, so thank you very much.
Nothing is fixed. Watch the video. It is taken today with PTS 8.0. The problem is still there. It cannot even do it without damage from the garage to the trailer store at Smithwille Dam. The problem is wrong mass processing and bad suspension settings.
Did some testing with Trapezium + Fuel Tank on 8.1 and it looks like it's finally driveable.
@KiDdYoNe Care to reveal what was done to fix that? Suspension height is the same as in version 8.0, so what exactly was changed?
Thank you.
