For the rear springs you can use the attached excerpt from the 1948 Vehicle Info Kit as an indication. Note that it's a "loaded" dimension, so if your tailgate is less than 25-3/4" above the ground with the truck bed empty, then your rear springs are definitely sagged.
Attachments
1948 Chevy Truck dimensions.jpg (14.03 KB, 99 downloads)


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.