The Stovebolt Site Forums The Shop Area Driveline Picture of 1950 3100 leaf spring rear end

3100?

It looks like you have a helper/auxiliary spring set.

That was not a GM option.

It looks like a 3100 could have had optional heavy duty rear springs (1 more leaf, I think) but no auxiliary springs are listed for 3100/3600.

Aftermarket auxiliary springs were available (from JC Whitney, as one example).