The only true side draft units that come to mind in the one from the 54 corvette 235 and the Nicson one. I think the Nicson used Zenith carbs.
I am with wolffcub. '53 and '54 vette ran three Carter YH carbs. The Nicson unit had the same flange bolt spacing but was designed for the smaller bore Zeniths in an unheated racing application. Here's a pic of the Nicson with spacers to adapt the Carter YH base:
Some suggest that this design predates GM's offering. My research has not been able to verify that.
Both designs are balance pipe affairs (not logs) - with a dedicated carb per intake runner. The GM unit is beefier
with provisions to bolt to the exhaust manifold stove for heat.
