I had a Suburban...Gutless, only about 16 mpg the best..Had to overhaul the pump at about 120k miles.. $1100... Gas Subs of that vintage were getting about 14.... I'm a diesel fan, Dodges and Duramax I have now....Wouldn't recommend 6.2 at all...And they smoke, too....and they're noisy too (ya, I know, not quite as loud as the ol' Cummmins) 

Oh, almost forgot--always had to wait for glow plugs to do the magic.. And it will NOT start if the system malfunctions-even in the summer...  Gotta sshhh that whiff of ether in 'er......