Where to get 16.5" throttle cable

The E-body cable has a completely-different arrangement at the firewall. It uses a square plastic snap-in grommet rather than the round metal ferrule. This is true of the later cars as well, such as F, M, R, and J-bodies along with the '71 & newer B-bodies. They all had a square hole in the firewall. I've never tried to reshape that plastic with a dremel or such, but it's pretty durable stuff.