Wel i would think he means it is 7200GVW instead of the 8600that most 3/4's have. if the truck is good you might be able to boost the rear springs but your better off to get the right size from the start .
I am not an expert on chevy trucks, by any means. Only i do know that most spreader manufactures require 8600 gvw for v-boxes. Which means ya need a Heavy Duty 3/4 ton. However there are smaller v-boxes made by companies like downeaster (sandpreader.com), that are lighter and may work in a ld 3/4 ton.
Another difference between the LD 3/4 and the HD 3/4 is the transmissions..both auto and manual. With the LD 3/4 you get the lighter duty 4L60-E automatic, or the light duty 5 speed..but i believe you can special order the HD 5 speed with bulldog low in the LD 3/4. In the HD 3/4 you get the 4L80-E 4 spd auto which is the heavy duty automatic, or the heavy duty 5 speed with bulldog low. You automatically get either of these when you specify which type of tranny (auto or manual) when you order an HD 3/4.
One thing I forgot is..you could get a diesel in that model year in a 1/2 ton, 3/4, and 1ton. All trannys were HD autos or HD manuals with the diesel..even in the 1/2 ton.
I have a 2500LD with a v-box in it,its only a 1yd so its fine,but i wouldnt want one any bigger in the back.I have had both a HD and LD 3/4 tons.I preffer the LD for 99% of my work.If you must have a big v box-just go straight for the 1 tons-they will handle it without the need for airbags or helper springs.The LD is much quicker with a 350,than the HD and handles the plow weight much better than the HD.The 4L60 trans thats in the LD is fine up to about 13K total weight,but its not as strong as HD trans 4L80E.