PD4106 Interior Alum Caps at the front and rear.

[TEAKNE]

Being the 4106 does not have a frame like other busses.  Can the interior front and rear aluminum caps be replaced with plywood or do they need to be kept for structural purposes? I would like to get rid of them due to the large amount of heat that radiates from them during the summer.   
Thanks!

[Red Rider]

Maybe you could make a "sticks and staple Bus' !

[RJ]

Teakne -

Are you talking about the front roof cap by the destination sign, as well as the rear window surround cap?

If so, both of those on a 4106's exterior are made from steel, not aluminum.

The interior caps in those areas are made from aluminum.

Are they structural?  Good question, but, IMHO, based on the few thousand rivets GMC used to retain them, I suspect that they are to some degree.  Reason I say this is because if you've ever sat in the back of the coach while it's going down the road (especially a rough one), you can see the chassis flexing.  Between the steel outer and aluminum inner caps, I believe these help to keep the bus roofline "square" to the floorline. But I'm also not a structural engineer, so take that for what it's worth.

That being said, I have seen numerous GMCs that have reconfigured the interiors with wood in the areas you're talking about, but have no knowledge of how the work was done.

FWIW & HTH. . .