Im going crazy trying to get out these bolts.

[ilyafish]

It was days of trying many things on those darn screws until a lightbulb went off and said 'get that grinder'.  Ever since then, if the screw looks like it wont come out....grinder it is.  I wont even bother trying.

PS....i was told a few times that the yellow inner panels are not structural.  I'm now confused!

[Oregonconversion]

Looks like I can get some out with a blow torch. Heating them up to 900F and then use the impact driver.

Some will still need a grinder looks like.

[JackConrad]

PS....i was told a few times that the yellow inner panels are not structural.  I'm now confused!

    It depends on who you talk to.  I have been told by some that that they are structural and by some that they are not structural. None of these people were MCI engineers. I doubt that anyone at MCI would want the liability of telling you to modify anything on an MCI bus.
    That said, here is what we did. At the time, I didn't even think about wether they were structural (it just didn't enter my mind). I removed all the inner panels, drove the bus to Lakeland (about 90 miles), had the bus sprayfoamed and drove it home. After grinding down the excess foam, I covered the walls with 1/2" plywood, I attached the plywood using#10 (3/16") screws at the same spacing as the OEM rivets (new holes) and also used urethane construction adhesive. About a week after I finished installing all the plywood, a fellow busnut asked if re-installed the aluminum panels.  with the plywood glued as well as screwed, it was not going to get changed. My original reason for not re-installing the aluminum panels was that with them attached to the framing members as well as the outside skin, they would serve as radiators transferring outside air temperature (hot or cold) from the putside skin through the framing members to the inside aluminum panels.  42,000 miles and no problems so far.  Just "our way", YMMV.  Jack