The GMC engine is certainly better than the 216-235 low oil pressure engines,but I'm not so sure if they are better than the 54 and up 235-261 Chevy.I could never find any hard facts stating a GMC lasted longer than a Chevy in normal duty truck use.It's all subjective stories from days long past.
For vintage hi performance use the GMC has more potential than the Chevy.In fact,back in the day,a built GMC could run away from a hot Flattie Ford V-8 and be more durable at the same time.
In the real world of today with a vintage truck living a live of luxury compared to the beating they used to get,there's no real difference between a Chevy or GMC other than a GMC truck should have a GMC engine.
