Correct! The dubbed "Fast Ratio Idler arm" is nothing more than a standard C-body idler are (~1970 ish). It always has been, and always will be. No-one ever "invented", created or designed the "fast ratio idler arm". Those who advertise it is simply selling the C-body idler arm and tagging the marketplace dubbed name onto it ("fast-ratio idler arm"). The factory overlooked installing it on the assembly line of the e-bodies when the Fast Ratio PS box was offered in late 70... and carried on for a brief time into 71 for the e-bodies with 340 engine options only. They knew it and determined the added cost and details to get it onto the assembly line were not worth the hassles as the option was soon to be discontinued. I'd spoken with Chrysler personnel in the late 70s about this and that's what they told me. There are no splines to be concerned of when installing the idler arm. The "Fast Ratio Pitman Arm" has splines that require proper one-way-only alignment to the gear box.