1988 chevy suburban diesel --help

I am looking at an 88 suburban to buy. What are the particular problems with this year? Even though it has only 128,000 original miles the motor and transmission have been replaced and it is now in the shop undergoing some motor problems (pistons). Is this normal or a bad sign?
Also, what is the best year for chevy or gmc diesel burbans?

Just one other thing--did they make 88 burbans in black that year?

Thank you very much for any info.