Back up here.
Your PO says chaasis battery. Than you talk about the coach battery.
Starting battery is chassis battery.
Are you using the radio? Is your step turned off.
A Scan Gage will draw down a chassis battery also.
When I did mine. We slid big washers in the coils. This made the springs longer.
After conn. the spring ends. Just remove the washers.
We also pushed the jacks up in store position. This was the hard part.
Boy if u got all that going that fast don't ever get rid of that 1 as very unusual mpg as that is a 2 v eng not the 3 used on newer 1's
what size & weights???
You still only get the 2 valve engine in a E450.
The 3 valve is in the class A chassis.