Vacuum:

Steve,

Your post about vacuum came in just after I sent my Zemco post.  My two bus 
installations were on a '72 and a '84 (current).  Both had sufficient 
vacuum for the Zemco units.  In other words, the cruise would hold full 
throttle whenever necessary.  Perhaps the Zemco design requires very little 
vacuum.

When I did my first bus installation, I worried about the vacuum motor as 
you pointed out.  However, an engineer friend who worked for a portable 
generator company, warned that the electro-mechanical controls had poor 
repeatability (speed variation) and were not very reliable.  His experience 
was in holding engine speed constant over varying generator loads rather 
than automotive use though.  So, I tried the Zemco in the '72 and had no 
problems whatsoever, except for hills that even full throttle couldn't 
remedy.

I agree about the sensitivity adjustment.  Yes, the Zemco has one.

I disagree about the vacuum canister.  I think that the vacuum motor always 
leaks so as to make it fail-safe.  Thus while the canister may help at 
first, it probably wouldn't last on a long hill.  Besides, on neither of my 
bus installations did I see any sign of running out of vacuum.

The only bus issue that I see is that the control head cable has to be 
extended as you pointed out.

Mike