172,700 and still runs 15.3s in the 1/4,and 9.8s in the 1/8.I love my 350. Tows great as well,I pull a 24 foot travel trailer a lot durin deer season.I love the 5.3s also.

 

my uncle has a vortec 350 in his 99 burban and it also knocks....but mine knocks louder

 

I switched to the new truck when i had my 5.7 vortec with JBA headers,hypertech,volant,catback.The truck ran well but my buddy with his 5.3 new truck and 200 miles on it started pulling away hard at 65 mph.Nothing wrong with the old vortec but just doesnt respond to mods as well as the Ls1s IMHO

 

Mine just has piston slap on cold days, for about a minute or so.

I've raced a 00 Z71 heads up a few times (a buddy) and he used to pull away from me around 60mph but I only have 3.08 gears. I think once I put in some 3.73's and maybe increase the shiftpoints a little bit I will surprise some guys.

 

I had a 96 K2500Hd ex cab long bed 4x4 with 350 vortec 5 speed.It was my first new vehicle,had 7 miles on it when I drove it off the lot.I hauled 5,000 lbs of shingles in the bed more times than I can remember.Pulled huge,overweight trailers(20,000-24,000 lbs)mud bogged it and it never missed a beat.When I traded it for my 2002 HD 8.1 it had 183,000 miles,only things replaced were 5 headlights,brakes and tires.While down on power from the new rides it was as reliable as a anvil.My 2002 8.1 burned more oil in 10,000 miles than the 5.7 did in 183,000.No slappin or other odd noises with mine.The fuel pump had the annoying buzz though.

 

I had a 95 GMC Ext cab that was bone stock and that thing would spin the tires from here to next week and had lots of low end torque, but now I have an extended cab 99 5.3 and it doesn't spin like the 5.7 but it will definently get up and pull harder from 60 MPH.

 

The 5.7 truck i had with all the mods towed my 26ft travel trailer well,the 5.3 with exhaust pulled even better and the truck handles it better .The 5.3 has the flat torque curve,it does ok in drive on some hills but on steep hills go into 2nd gear and go 3500-4000rpm at 50-60 mph at 1/2 throttle not laboring.Now my 6.0 is a whole nother storie.

 

John, the L31 was rated at 255hp (you may see it listed at 260 also), but not 280.

I had it in my 97 Tahoe. Great, smooth, and powerful (for it's time).

It was the old school SBC so it was a very tried and true, well tested platform. It's heads flow great for the cost and are a popular "hot rod" head for those on a budget.

It towed my trailers without question. I never ran it at the track so I have no times on it either. The one thing I like about it over my 8.1 was that it wasn't burdened by a HD Allison transmission. Under normal driving conditions, it never had to rev more than 500rpm in each gear to sufficiently get it up to speed. Whereas when my 8.1 spinning through the Allison when unloaded is accelerating, it seems to have to rev a little bit more to counter it.