The mounting bracket for the Kick down switch has a mounting Tang (outboard), that is bent down and interlocks with a hole in the base of the carb (outboard of the rear carb mounting stud hole) (Mine is a quadrajet 4MV) this tang keeps the switch and bracket from rotating and maintains the switch in-line with the actuating arm that is mounted on the throttle shaft. The kickdown switch bracket must be installed under the power brake pipe tube mounting attachment.
The switches are servicable, by carefully peening open the Zinc case, you can access the internals and burnish or buff-bright the stationary and sliding copper contacts and relube the switch for care free operation. Make drawings or notes on assembly order and do not stress the zinc case. It can be done (I HAVE REWORKED 2 SWITCHES) and save tons on purchasing a replacment from E-PAY!
I assume a 1969 Holley equiped, 396/375-TH400 with kick down would be same, not sure if the mounting bracket is identical or not.
My source is my 1968 396/325-TH400 I have had for 24 years.
The L/78 ( Holley ) bracket for the kick-down switch is different.