Checking compression is a good idea...does it crank evenly? If there is a cylinder that is really off the others, you can usually hear that when it cranks...instead of all of them sounding the same, when the cranking gets to the low compression cylinder, the cranking will speed up for a second...the sound will change on that one every rotation...
The muffler being ruptured wouldnt in itself hurt the motor, depends how it got that way......it is possible to do that by turning the on/off switch off while the truck is running....wait a few seconds (with no ignition to burn fuel) then turn it back on...especially if you are driving at speed...I saw it done...not pretty...
Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.
Pro-choice, that's a LIE, babies don't choose to die!!