I've been driving my mum's 1970 dyane for the last couple of weeks while the acad is getting some much needed tlc. Definately since i last drove it, but even over the last couple of weeks i've noticed the steering is getting a bit heavier, the doors don't quite shut as well as they used to and the (rod-operated) throttle is getting sticky. Also, both inner wings are suddenly catching on the driveshafts on bumps.

All these problems get worse when one or two passengers get in. Am i right in thinking the chassis is starting to bend and therefore is on its way out?

Well you've got all the ingredients here, so I guess so, take a good look at the chassis.....

Or the lower bulkhead/toe board is on the way out, which could give similar symptoms.
Is the steering column still (fairly) central in the hole through the bulkhead?

I'll have a look in the morning. i do know it doesn't self-centre whilst cornering if you let go... :/

When my bulkhead went, my D*lly got to the point where the doors would open on corners...