Just bought a 1997 GMC Sierra 1500 yesterday - should I use 1st gear?

the old 4 speed tranny you could use second to take off but they where geard really low.if it was my truck with a 5spd I would drive it using first,this way you don't put unecesary strain on the cluth and pressure plate and your clutch will last longer.

Mine is a 5sp also with a 5.0 engine and extended cab. I use my first gear every time. I can't tell from the way you wrote your question, but to drive for any amount of time in first gear would not be recommended unless you had a heavy load and going very slow. Is that what you mean? Like traveling up hill with a heavy load you may not want to go in 5th gear.