I don't have a full '72 brochure but in '71, the 3:55 was only optional on LT1 and LS5 & LS6 big blocks.

 

Whether ordered from the factory or purchased off the lot, the following ratios were available. 2:72, 3:08, 3:36, 3:55, 3:70, 3:90 and 4:11. The most common ratios installed for off the lot sales were the 3:08, 3:36 and 3:55. If somone wanted an Autobahn cruiser they could order the 2:72's or if they wanted a hole shot king, the 4:11's.