How to expand the van.
I'm doing this mostly from memory. I used M820 vans about 30 years ago.
1. Unhook the safety chains that are attached to the sides of the liftgate.
2. Lower the tailgate to the ground and remove ladders. The liftgate is controlled by two levers. One with a red plastic coated handle and controls the tilt of the liftgate. The liftgate is raised and lowered by attaching a handle to the bent levers under the back corners of the box. To lower the liftgate to the ground, engage the PTO. Tilt the liftgate to its horizontal position by pushing the straight lever with the coated handle towards the rear. The tailgate is lowered by attaching a handle to one of the bent levers and lifting up first to disengage the safety locks. Then lower the tailgate by shoving the lever down.
3. The M820 has four leveling jacks. The leveling jacks go under the corners of the box when expanded. The leveling jacks are not required, but they make the box much more stable. Because of what we used them for, our vans required them to be leveled before we could start working. Remove the 4 leveling jacks and base plates from their storage location behind the cover under the center of the back doorway.
4. You have to open the two back doors to access the cranks to extend the sides.
5. First unlatch the safety latches at the lower corners of the box. I believe that there are cotter pins holding them. At each corner of the box, there is a hinged rod (about 4 or 5 feet long) that is used to secure the box sides when expanded. Keep the rods safely out of the way until the box sides have been extended and cranked tight again.
6. The crank for the doors is supposed to be stored in a bracket fastened to the door (if missing, you can use a large wrench with socket and extender). Put the handle on the hex shaft and flip the lever to disengage the pawl so that the sides can be cranked out. Crank the sides completely out. Flip the hinged side panels out from inside at each corner. These need to be out of the way so that the floor and ceiling panels can be opened.
7. Duck under the opened side and reach up to the center of the box and unlatch the Floor/roof panels.
8. Pull the floor out and down until it rests on the rails that are supporting the extended sides (you might need to get inside the box and push the floor/ceiling panels out.) The roof panel is linked to the floor panel by cables and will flip up at the same time as the floor panel lowers.
9. Now flip the side panels hinged at the corners back in to enclose the box corners. Climb into the box. There is a metal guide that can be extended to help keep the corner panels aligned when closing the box sides.
10. There are 3 hooks (attached at the upper edge of the sidewalls) that should be extended (pointing toward the center of the box). Push up on the ceiling to extend the hooks. These will help guide the ceiling panels when the sides are cranked in.
11. Flip the ratchet pawl. Slowly crank the sides all the way in, paying careful attention to the corner panels.
12. Climb inside the box and fasten the roof latches to the hooks at the upper edge of the sidewalls. There are 3 of them on each side.
13. When the sides have been cranked in and the roof latches fastened, you should lower the hinged rods on the outside corners of the box and use them to tighten the corners down with the safety latches that you first unfastened in the beginning.
14. Install the leveling jacks (if desired) by attaching the baseplate and attaching the top of the jack to a mating flange under the box corners and twisting it to lock it in place.
15. As these vans are prone to leaking, it is best to have a tarp that covers the entire top of the van to keep out the rain. Tie down the tarp to keep it from blowing away in the wind.
When closing up the van for moving, reverse these steps. Attach the ladders to the back doors and secure (if not stored inside the box). Ensure they are kept from moving around by using ropes and/or bungees. I think they have some screws and washers that help to fasten them down. To stow the liftgate, raise it and tilt it up vertical. Try to lower it again to ensure that the safety locks have engaged. Disengage the PTO. Attach the safety chains to the edges. Stow the lift handles.
The liftgate can be used as a raised platform if some kind of bracing is used under it and a safety chain put around the sides. There should be some holes around the sides of the liftgate for posts linked together by chains. The ladders can then be attached to the sides of the liftgate. Alternately, the ladders can be attached to the side doors.
