1. additional leg room about 2", unless the seat hits the batteries
actually the seat back nearly hits the back of the cab even with the tank in
2. no smell if the system is in proper good shape, ya think GM woulda sold many of these things new if they stunk of gas?
3. rear tank puts weight
behind the wheels, affecting the steering - in the cab it keeps the right front/rear ratio when carrying a load, it is a truck after all
4. batterie[s]? ... need extra w/ a corvette engine?
5. nice to stretch yer legs every 2-300 miles and take a leak
of course a vette engine may drink more
I vote for using the time to have fun or do more important jobs, and spend the money more usefully, and I see too much of
this kinda wreck nowadays 
Bill
