You should use 10W 30 of any good quality oil.
SAE 10w30 any major brand.
A quality filter such as AC/Delco is the filter your should use.
5 quarts
I know on a1987 Suburban the oil pressure switch is located just above the oil filter. Check there. it might there on the '88 also.
The 2003 Chevrolet suburban requires five quarts of oil in the motor. The oil filter should be filled with oil, when changing it.
For a 2003 Chevy Suburban (all engine sizes), the recommended viscosity is 5W30.
80-90 PL-5 gear oil
Dextron II fluid.
SAE 75W90 synthetic gear oil
10w30
I assume you mean transfer case. The answer is dexron 3
It should be SAE 10W30 weight. I like Castrol GTX in mine, but there are a lot of very good oils on the market.