On a Cadillac, or Buick of a similar year. Where it was a rare option on the entry level Chevrolet, it was standard equipment on the more expensive marquees.

Big Dave

 

Trucnk release

The 1966 Vacuum truck release was a delaer installed accessory and not a factory option. You'll find components for it and once in a while the entire until on eBay. It can get pretty pricey.
There are many parts so make sure you have them all before trying to install.

Paul Winvoices

 

Trunk release

Donny deals in loads of NOS parts, he said he has one and lasted me to sent you his e-mail:

fh348@comcast.net

Paul

 

Thanks i sent him a mgs

 

I bought both pieces separately on Ebay for my 68, but be sure to get the correct vacuum release mechanism. There is a coupler needed to extend the lock arm but I got around that by buying an extra long replacement rod. It extends a good inch through the trunk lock. Only paid about $125 for the whole set up. Works great. I had to put the pump/ knob under the dash because my car has A/C and the glovebox is attached to the door and moves up and down. Don S

 

I installed this one from a 65 Oldsmobile on my 65 Impala. Still need a little tinkering but it works.