carb

[Mr70]

What's the date code showing on your 3310?
That was originally issued for the 1965 Z16 & some L-78 Chevelles,but was also re-released in major quantities later on to satisfy the restoration market by Holley.


That 4053 DZ is a later service replacement assembled on April 2nd,1971-81-91..also re-released by Holley to satisfy the restoration market.
It originally came on solid lifter:
*1968-69 Z/28 Camaro & 1968 396 L-78/L-89 Camaro.
*1968 396 L-78 Chevelle-Chevy II & Big Passenger series cars w/427 L-72.