I have a set of original AAR hood springs. They measure 5 1/2" long, 33 coils, 1 5/16 OD, the spring thickness measured with a micrometer is .166 . I have a set of NOS TA hood springs, purchased from Chrysler in the 70's, no dealer sticker but I know who bought them. They measure 6 1/2" long, 36 coils, 1 5/16 OD, the spring thickness is .180 . The spring thickness is more on the TA springs I have, not sure if the over the counter springs were the same as the production line springs, they are gold cad plated. The hooks are also different between the two springs! These springs are unique to just the AAR and the TA.